Preparation method of ternary positive electrode material precursor

Abstract

The invention relates to the field of precursor preparation, and relates to a preparation method of a ternary positive electrode material precursor, a preparation system is adopted, and the preparation system comprises a reaction container, a stirring piece, a dispersion container and a dispersion mechanism; the preparation method comprises the following steps: inputting raw materials into a reaction container, stirring the raw materials by adopting a stirring piece, and monitoring the reaction stage of the raw materials; when the reaction stage is in the initial nucleation stage, reactants in the reaction container are gradually transferred into the dispersion container; carrying out primary dispersion depolymerization treatment on the reactants transferred into the dispersion container for the first time through the dispersion mechanism, and gradually transferring the reactants in the dispersion container into the reaction container; when the reaction stage enters a later growth stage, gradually transferring reactants in the reaction container into the dispersion container again; carrying out secondary dispersion depolymerization treatment on the reactants transferred into the dispersion container again through the dispersion mechanism; in the secondary dispersion depolymerization treatment process, reactants in the dispersion container are gradually transferred into the reaction container.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precursor preparation, and in particular to a preparation method of a ternary cathode material precursor. BACKGROUND

[0002] With the rapid development of science and technology, lithium ion batteries have been widely used in electric vehicles, portable electronic devices and other fields due to their high energy density, high specific capacity, high specific power, long cycle life, fast charging and discharging rate and many other advantages. In order to meet the growing demand for energy density, high specific capacity, good safety and low cost ternary cathode material (LiNi x Co y Mn z O2, x+y+z=1) has gradually become a research hotspot in the field of cathode materials. The performance of the ternary cathode material directly determines the capacity and performance of the battery, and the performance of the ternary precursor plays a decisive role in the performance of the ternary cathode material. The synthesis of the ternary precursor highly depends on the precise control process. Currently, the co-precipitation method is usually used to prepare the ternary cathode material precursor in industry. This method is to synthesize a mixed solution with different nickel-cobalt-manganese ratios, a complexing agent, a precipitating agent, a doping agent and the like under suitable conditions, and then to produce the desired precursor. Among the many indicators for evaluating the precursor, sphericity is a key indicator. Good sphericity can effectively improve the tap density of the ternary cathode material, prolong its cycle performance, and improve its rate performance. Therefore, how to improve the sphericity of the precursor has become a crucial technology. In the synthesis reaction process of single crystal, high power and other ternary precursors, in order to improve the sphericity of the product, the traditional method is usually to control the reaction conditions such as pH value, stirring intensity, ammonia concentration and temperature to control the reaction process. These control methods can make the mixed reaction more stable to a certain extent and achieve certain control effect. However, for small particles (median diameter ≤ 4.5 μm) products with single crystal type and good sphericity, the above control methods face great difficulty. Especially for the cathode material with high cycle performance, a large number of agglomerated particles are often produced during the nucleation and growth of the precursor. In the later growth stage, it is difficult to depolymerize the soft agglomerated material into independent primary spheres with good dispersibility, and the traditional method also has the disadvantages that the nucleation amount and nucleation rate at the initial stage of reaction are not easy to control, which leads to difficult to achieve more stable control effect.

[0003] Therefore, how to solve the problems existing in the prior art has become the research and solution of the present application. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of a ternary cathode material precursor.

[0005] To achieve the above object, the technical scheme adopted by the present application is: A preparation method of a ternary positive electrode material precursor, adopts a preparation system, the preparation system includes a reaction container, a stirring part, a dispersion container and a dispersion mechanism; The preparation method includes: Step one, input raw materials into the reaction container, the raw materials include metal liquid, complexing agent and precipitating agent; Step two, use the stirring part to stir the raw materials in the reaction container, and monitor the reaction stage of the raw materials; Step three, when the reaction stage is in the initial nucleation stage, gradually transfer the reactants in the reaction container into the dispersion container; Step four, the dispersion mechanism is used to perform primary dispersion depolymerization treatment on the reactants initially transferred into the dispersion container, so as to achieve the purpose of nucleation; Step five, in the process of primary dispersion depolymerization treatment, gradually transfer the reactants in the dispersion container into the reaction container; Step six, when the reaction stage enters the later growth stage, the reactants in the reaction container are again gradually transferred into the dispersion container; Step seven, the dispersion mechanism is used to perform secondary dispersion depolymerization treatment on the reactants again transferred into the dispersion container, so as to promote the uniform dispersion of the reactants and perform the co-precipitation reaction; Step eight, in the process of secondary dispersion depolymerization treatment, gradually transfer the reactants in the dispersion container into the reaction container.

[0006] In the above scheme, the following is explained: In step one, the raw materials can be 1.0-2.5 mol / L (also can be said to be 1.0 mol / L-2.5 mol / L) metal liquid, 2-5 mol / L complexing agent ammonia water, and 5-10 mol / L precipitating agent sodium hydroxide, which are input into the reaction container through the feeding pipe; In step two, the stirring treatment is provided, which can refer to the existing stirring instructions, and the monitoring method such as scanning electron microscope also uses the existing settings; In steps three to five, the dispersion depolymerization treatment is introduced in time in the initial nucleation stage, the nucleation amount and nucleation rate of this stage are controlled, and a large number of agglomerated particles are avoided in the initial stage; It should be noted that if a large number of agglomerated particles have been generated in the initial stage, the stirring effect will be greatly reduced, resulting in more dispersion depolymerization in the subsequent stage relying on the dispersion mechanism; In steps six to eight, the dispersion depolymerization treatment is introduced again in time in the later growth stage, which can effectively inhibit the particle agglomeration, ensure the uniform dispersion of the reactants to realize stable co-precipitation reaction, and thus optimize the morphology and composition uniformity of the precursor.

[0007] The collection process of the precursor is known and will not be described here.

[0008] In summary, as the slurry density increases after the reaction stabilizes, the stirring load increases, and several individual small balls are easily aggregated and adhered to form two or more small balls, forming agglomerates in the form of embedding, fusion or other aggregation, which has a great influence on the product morphology, particle size distribution, specific surface area and other properties, thereby affecting the performance of the positive electrode material. In the present application, the stirring treatment and dispersion depolymerization treatment are carried out in a coordinated manner, the nucleation amount and nucleation rate at the initial stage of the reaction are effectively and accurately controlled, and the particle agglomeration is effectively inhibited at the growth stage. The uniform and dispersed product is beneficial to the preparation of single-crystal ternary precursors with good dispersity.

[0009] In some embodiments, the stirring speed is controlled to be 200 rpm to 700 rpm; the temperature of the material (reactant) in the reaction container is controlled to be 40°C to 70°C; the pH value of the material in the reaction container is controlled to be 11 to 13; the concentration of ammonia water is 2 to 5 mol / L; the concentration of sodium hydroxide is 5 to 10 mol / L; the circulation amount of the reactant is controlled to be 3 to 8 m³ / H, preferably 5 m³ / H; and the intensity of the ultrasonic generator is 20 to 100 KHZ, preferably 40 to 60 KHZ.

[0010] To highlight the advantages of the present application, the following existing patents are compared: Patent 1: Chinese patent CN111196613A discloses a preparation method of high-spherical ternary precursor seeds and a method for preparing high-spherical ternary precursors using the seeds. The method adds solid particles that are insoluble in the bottom solution to the reaction synthesis bottom solution to increase the solid content in the bottom solution, so that the small seeds generated by the reaction are difficult to aggregate under the dispersion of the solid particles, thereby avoiding the agglomeration of small seeds and preparing high-spherical seeds. The method can realize continuous production, and the prepared high-spherical seeds can be used as seeds for producing high-spherical precursors in the next step after being stored in a seed tank, or can be used as small-particle precursors after processing. Patent 2: Chinese patent CN113912140A discloses a method for preparing ternary precursors and a reaction device. The co-precipitation reaction is carried out under the joint action of the inner container, the stirring mechanism and the hard ball. The specific steps are as follows: configuring a metal salt solution with a molar concentration of 1 mol / L to 4 mol / L, configuring a precipitating agent with a molar concentration of 9 mol / L to 12 mol / L, configuring a complexing agent with a molar concentration of 6 mol / L to 9 mol / L, and carrying out intermittent co-precipitation reaction until the particle size D50 meets the requirements. This intermittent method can prepare ternary precursors with narrow diameter and high sphericity. Patent 3: Chinese patent CN113996251A discloses a preparation equipment and method of ternary precursor, the preparation equipment includes a reaction kettle body, a liner, a feeding mechanism, a stirring mechanism and a hard body, the peripheral wall of the liner is provided with a first discharge hole, the feeding mechanism is used for conveying materials to the reaction kettle body, and the hard body is movably located in the liner; by increasing the collision frequency and collision times of the slurry and the hard body, the small particle nickel-cobalt-manganese ternary precursor is promoted to form a high sphericity in a short growth time, the dispersion of the material in the reaction system is effectively improved, and the problem that the existing ternary precursor with good dispersion is difficult to prepare is solved; The above patents all adopt the mode of adding solid particles or similar substances (solid particles are described below), and the slurry collides with the solid particles through stirring to achieve the effect of particle dispersion; but this mode has the risk of introducing foreign matter, and the separation of the slurry and the solid particles is difficult, and the collision of the solid particles with the stirring structure and the like is also not conducive to the long-term use and maintenance of the equipment; the present application avoids the above problems without adding solid particles.

[0011] Further technical solutions, the dispersion mechanism includes an ultrasonic generator, a connecting line and a dispersion rod connected in sequence; The dispersion rod serves as a component for dispersing and depolymerizing the reactants; In step four, the output power of the ultrasonic generator is set to A; In step seven, the output power of the ultrasonic generator is set to B; The A and the B satisfy: A=B.

[0012] The ultrasonic generator, the connecting line and the dispersion rod are existing devices, and the principle of combined use is not described here. In the working process, the dispersion rod contacts the reactants, which can prevent the formation of soft agglomerates during synthesis and can disperse the soft agglomerates after their formation.

[0013] In the present application, the output power of the ultrasonic generator in different stages is the same, on the one hand, there is no need to frequently adjust the power in different stages, which reduces human operation errors (such as parameter setting errors, improper adjustment time, etc.), especially suitable for the scene of this application which requires high degree of automation and operation efficiency; on the other hand, frequent switching of the power of the ultrasonic generator will cause the internal electronic components (such as power tubes and capacitors) to bear repeated current surges, which will shorten the service life of the equipment in the long run, and constant power operation can reduce such losses and prolong the stable working time of the equipment.

[0014] Further technical solutions, in steps one to eight, the stirring part continuously stirs the reactants in the reaction container.

[0015] The dispersion mechanism only works in part of the time period, while the stirring member stirs the raw materials in the whole time period of the reaction, controls the particle growth rate and morphology (such as avoiding agglomeration and maintaining sphericity) through a stable flow field environment, and ensures the consistency of the performance of the final product.

[0016] Further technical solutions, the dispersion container has a feed inlet and a discharge outlet, the feed inlet is arranged at the bottom end of the dispersion container, and the discharge outlet is arranged at the top end of the dispersion container. In steps three and six, the reactants in the reaction container are transferred into the dispersion container through the feed inlet; In steps five and eight, the reactants in the dispersion container are transferred into the reaction container through the discharge outlet.

[0017] The feed inlet is arranged at the bottom end of the dispersion container, and the discharge outlet is arranged at the top end of the dispersion container, based on which a downward and upward flow path is formed. When the feed inlet is arranged at the bottom end, the reactants flow upward naturally under the action of conveying pressure and buoyancy, prolonging the path length and residence time of the reactants in the dispersion container, which is suitable for the scene of the present application which needs to be fully dispersed and depolymerized.

[0018] In some embodiments, along the radial direction of the dispersion container, the feed inlet and the discharge outlet are arranged at the symmetrical two ends of the dispersion container.

[0019] Further technical solutions, the preparation system further comprises a first material conveying pipe and a flow meter; In steps five and eight, the reactants in the dispersion container are transferred into the reaction container through the first material conveying pipe, and the flow in the first material conveying pipe is monitored through the flow meter.

[0020] The specific material and other settings of the first material conveying pipe and the type of the flow meter are not limited, as long as the above-mentioned purposes can be achieved.

[0021] The reactants in the dispersion container are transferred into the reaction container through the first material conveying pipe, in addition to which, a pneumatic pump can also be introduced, and the reactants are transferred through the pneumatic pump. The reactants in the reaction container can also be transferred to the dispersion container through the material conveying pipe.

[0022] The present application introduces a flow monitoring device to avoid the situation that the residence time of the reactants in the dispersion container is short due to the flow of the reactants being higher than the predetermined value during the transfer, and to ensure the dispersion and depolymerization effect. The principle of the combination of the first material conveying pipe and the flow meter is well known, and will not be described here.

[0023] Further technical solutions, the preparation system further comprises a sampling member; In step four and step seven, the sample is taken from the dispersing container by the sampling device, and the sample is detected, and the dispersing and depolymerization settings of the dispersing mechanism are adjusted according to the detection result.

[0024] The sampling device can be a conventional sampling ball valve. The sampling process of the sampling device is not limited.

[0025] The sample detection method is conventional and not limited. For example, a scanning electron microscope is used to determine the dispersing and depolymerization effect according to the scanning electron microscope image, and then the dispersing and depolymerization settings of the dispersing mechanism are adjusted, such as adjusting the output power of the ultrasonic generator, to realize the closed-loop control logic of “sampling detection-result feedback-parameter adjustment” and guarantee the dispersing and depolymerization effect.

[0026] Further technical solutions, the preparation system further comprises a second material conveying pipe and a moving base; In step three and step six, the reactants in the reaction container are transferred into the dispersing container through the second material conveying pipe; The dispersing container is fixed on the top of the moving base, and the fluid flow path in the second material conveying pipe is adjusted by the moving base.

[0027] The specific material and other settings of the second material conveying pipe are not limited.

[0028] The specific structure of the moving base is not limited, but it is exemplified here that it can include a base body and a plurality of universal wheels to form a moving trolley structure, so that it can be freely switched to be installed on other reaction containers, and it can be used at any time, which is simple and convenient to operate, and is suitable for large-scale production.

[0029] The reactants in the reaction container are transferred into the dispersing container through the second material conveying pipe, and in addition, the following settings can be introduced: First, an electromagnetic valve is installed on the reaction container or the second material conveying pipe to control the outflow process of the reactants; Second, the height of the reaction container is higher than the height of the inlet of the dispersing container; Third, a conveying pump is introduced to ensure that the reactants have enough power to enter the dispersing container.

[0030] If the second material conveying pipe is spirally arranged, the fluid flow path in the second material conveying pipe is a spiral path. Through the arrangement of the moving base, on the one hand, the dispersing container and the dispersing mechanism can be conveniently transferred; on the other hand, the fluid flow path in the second material conveying pipe can be conveniently adjusted, for example, the fluid flow path is a straight line, so as to guarantee the outflow rate of the reactants.

[0031] Further technical solutions, the dispersing container comprises a corresponding assembled barrel and cover, and part of the dispersing mechanism is arranged in the barrel. The preparation method further comprises: Step nine, after the secondary dispersion depolymerization treatment is completed, separate the barrel and the cover, clean the barrel inner wall, the cover inner wall and the part of the dispersion mechanism placed in the barrel.

[0032] The shape, assembly method, etc. of the barrel and the cover are not limited. The cover can have openings corresponding to the above-mentioned structures, which are not limited.

[0033] Part of the dispersion mechanism is placed in the barrel, for example, a dispersion rod is placed in the barrel.

[0034] After the secondary dispersion depolymerization treatment is completed, the reactants are returned to the reaction container, and the stirring treatment can be continued. Finally, the reactants are removed from the reaction container and then continue to process the subsequent raw materials. By cleaning the barrel inner wall, the cover inner wall and the part of the dispersion mechanism placed in the barrel, on the one hand, it can avoid the gradual damage of these structures due to the corrosive properties of the reactants, on the other hand, it can eliminate the interference of historical residues on the reaction system.

[0035] It should be noted that the reactants gradually flow into the dispersion container and gradually flow out of the dispersion container, and the reactants do not need to be temporarily stored in the dispersion container and then discharged as a whole. Based on this, the capacity of the dispersion container can be much smaller than the capacity of the reaction container, and the dispersion container needs to be cleaned. The cleaning of the reaction container is not limited here.

[0036] As for the "first", "second", etc. used in this paper, it is not particularly intended to indicate the order or sequence, nor to limit the case, but only to distinguish the components or operations described with the same technical terms.

[0037] As for the "connection" or "positioning" used in this paper, it can mean that two or more components or devices are in direct physical contact with each other, or are indirectly in physical contact with each other, or can mean that two or more components or devices operate or act on each other.

[0038] As for the "contain", "include", "have" and the like used in this paper, they are all open terms, that is, they mean containing but not limited to.

[0039] As for the words (terms) used in this paper, except for special notes, they usually have the usual meaning of each word used in this field, in the content of the case and in the special content. Some words used to describe the case will be discussed below or elsewhere in this specification to provide additional guidance for those skilled in the art on the description of the case.

[0040] As to the "front", "back", "upper", "lower", "left", "right" and the like used herein, they are directional words, which are only used to describe the positional relationship between structures in the case, and are not used to limit the specific direction of the protection scheme and actual implementation.

[0041] The working principle and advantages of the present application are as follows: With the increase of slurry density after the reaction stabilizes, the stirring load increases, and several single pellets are easily aggregated and adhered to form two or more pellets in the form of embedding, fusion or other aggregation, which has a great influence on the product morphology, particle size distribution, specific surface area and the like, thereby affecting the performance of the positive electrode material. The present application adopts the mode of stirring treatment and dispersion depolymerization treatment in cooperation, effectively and accurately controls the nucleation amount and nucleation rate in the early stage of reaction, and effectively inhibits particle aggregation in the later growth stage, which is conducive to the preparation of single crystal type ternary precursor with good dispersion.

[0042] In addition, many existing technologies use the method of adding solid particles or similar substances (solid particles are described below) to make the slurry collide with the solid particles by stirring to achieve the effect of particle dispersion. However, this method has the risk of introducing foreign matter, and it is difficult to separate the slurry from the solid particles, and the collision of solid particles with stirring structures and the like is also not conducive to the long-term use and maintenance of the equipment. The present application avoids these problems by not adding solid particles. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 Structure schematic diagram of the preparation system of the embodiment of the present application; Figure 2 Flow chart of the preparation method of the ternary positive electrode material precursor of the embodiment of the present application; Figure 3 SEM image of Example 1;

[0044] Figure 4 SEM image of Example 2;

[0045] Figure 5 SEM image of Example 3;

[0046] Figure 6 SEM image of Example 4;

[0047] Figure 7 SEM image of Comparative Example 1. Figure 8 SEM image of Comparative Example 1.

[0048] In the above figure: 1, reaction container; 2, stirring piece; 3, dispersion container; 31, feeding port; 32, discharging port; 33, barrel; 34, cover; 4, dispersion mechanism; 41, ultrasonic generator; 42, connecting line; 43, dispersion rod; 5, first conveying pipe; 6, flow meter; 7, sampling piece; 8, second conveying pipe; 9, moving base; 91, base body; 92, universal wheel; 10, pneumatic pump; 20, electromagnetic valve; 30, conveying pump. DETAILED DESCRIPTION

[0049] The application will be further described below in conjunction with the drawings and examples: Examples: The present application will be clearly explained below by means of figures and detailed descriptions. Any person skilled in the art can make changes and modifications to the technology taught by the present application without departing from the spirit and scope of the present application.

[0050] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. The singular forms "a", "this", "this", "this" and "the" as used herein also include the plural forms.

[0051] Reference Figures 1-2 A preparation method of a ternary positive electrode material precursor, which adopts a preparation system including a reaction container 1, a stirring piece 2, a dispersion container 3 and a dispersion mechanism 4; The preparation method includes: Step one, input raw materials into the reaction container 1, the raw materials including metal liquid, complexing agent and precipitating agent; Step two, use the stirring piece 2 to stir the raw materials in the reaction container 1, and monitor the reaction stage of the raw materials; Step three, when the reaction stage is in the initial nucleation stage, gradually transfer the reactants in the reaction container 1 into the dispersion container 3; Step four, the dispersion mechanism 4 is used to perform primary dispersion depolymerization treatment on the reactants initially transferred into the dispersion container 3, so as to achieve the purpose of nucleation; Step five, during the primary dispersion depolymerization treatment, gradually transfer the reactants in the dispersion container 3 into the reaction container 1; Step six, when the reaction stage enters the later growth stage, gradually transfer the reactants in the reaction container 1 into the dispersion container 3 again; Step seven, the dispersion mechanism 4 is used to perform secondary dispersion depolymerization treatment on the reactants transferred into the dispersion container 3 again, so as to promote the uniform dispersion of the reactants and perform the coprecipitation reaction; Step eight, during the secondary dispersion depolymerization treatment, gradually transfer the reactants in the dispersion container 3 into the reaction container 1.

[0052] In the above scheme, the following is explained: In step one, the raw material can be 1.0-2.5 mol / L (also can be said to be 1.0 mol / L-2.5 mol / L) of the metal liquid, 2-5 mol / L of the complexing agent ammonia water, and 5-10 mol / L of the precipitating agent sodium hydroxide, which are input into the reaction container 1 through the feeding pipe; In step two, the stirring treatment is provided as existing, and the monitoring method can refer to the existing stirring description. The monitoring method also uses the existing setting. In steps three to five, the dispersion depolymerization treatment is introduced in time in the initial nucleation stage to control the nucleation amount and nucleation rate in this stage, so as to avoid the generation of a large number of agglomerated particles in the initial stage. It should be noted that if a large number of agglomerated particles are generated in the initial stage, the stirring effect will be greatly reduced, resulting in more dispersion depolymerization in the subsequent stage relying on the dispersion mechanism 4. In steps six to eight, the dispersion depolymerization treatment is introduced in time again in the later growth stage, which can effectively inhibit the particle agglomeration and ensure the uniform dispersion of the reactants to realize stable coprecipitation reaction, thereby optimizing the morphology and composition uniformity of the precursor.

[0053] The collection process of the precursor and the like uses the existing, which is not described here.

[0054] As described above, with the increase of the slurry density after the reaction is stable, the stirring load increases, and several single pellets are easily aggregated and adhered to form two or more pellets in the form of embedding, fusion or other aggregation to form agglomerates, which has a great influence on the product morphology, particle size distribution, specific surface area and the like, thereby affecting the performance of the positive electrode material. In the embodiment, the stirring treatment and the dispersion depolymerization treatment are cooperatively performed, the nucleation amount and nucleation rate in the initial stage of the reaction are effectively and accurately controlled, the particle agglomeration in the later growth stage is effectively inhibited, and the product with uniform morphology and dispersion is formed, which is conducive to the preparation of the ternary precursor with single crystal type and good dispersion.

[0055] In some embodiments, the stirring speed is controlled to be 200 rpm-700 rpm; the temperature of the material (reactant) in the reaction container 1 is controlled to be 40°C-70°C; the pH value of the material in the reaction container 1 is controlled to be 11-13; the ammonia water concentration is 2-5 mol / L; the sodium hydroxide concentration is 5-10 mol / L; the circulation amount of the reactant is controlled to be 3-8 m³ / H, preferably 5 m³ / H; and the intensity of the ultrasonic generator 41 is 20-100 KHZ, preferably 40-60 KHZ.

[0056] To highlight the advantages of the embodiment, the following existing patents are supplemented for comparison: Patent 1: Chinese patent CN111196613A discloses a preparation method of high-sphericity ternary precursor seed and a method for preparing high-sphericity ternary precursor using the seed. The method improves the solid content in the bottom liquid by adding solid particles that are insoluble in the bottom liquid, so that the small seed generated by the reaction is difficult to aggregate under the dispersion of the solid particles, thereby avoiding the aggregation of small seed and preparing high-sphericity seed. The method can realize continuous production, and the high-sphericity seed prepared can be used as seed for producing high-sphericity precursor in the next step after being stored in a seed tank, or can be used as small-particle precursor after processing. Patent 2: Chinese patent CN113912140A discloses a method and a reaction device for preparing ternary precursor. The co-precipitation reaction is carried out under the joint action of the inner container, the stirring mechanism and the hard ball. The specific steps are as follows: configuring a metal salt solution with a molar concentration of 1-4 mol / L, configuring a precipitant with a molar concentration of 9-12 mol / L, configuring a complexing agent with a molar concentration of 6-9 mol / L, and carrying out intermittent co-precipitation reaction until the particle size D50 reaches the requirement. This intermittent method can prepare ternary precursor with narrow diameter and high sphericity. Patent 3: Chinese patent CN113996251A discloses a preparation device and method for ternary precursor. The preparation device includes a reaction kettle body, an inner container, a feeding mechanism, a stirring mechanism and a hard body. The peripheral wall of the inner container is provided with a first discharge hole. The feeding mechanism is used to deliver materials to the reaction kettle body. The hard body is movably located inside the inner container. By increasing the collision frequency and collision times of the slurry and the hard body, the small particle nickel-cobalt-manganese ternary precursor is formed with high sphericity in a short growth time, effectively improving the dispersion of the material in the reaction system and solving the problem of difficult preparation of ternary precursor with good dispersion. The above patents all use the method of adding solid particles or similar substances (solid particles are described below) to achieve the effect of particle dispersion by stirring the slurry and solid particles. However, this method has the risk of introducing foreign matter, and it is difficult to separate the slurry and the solid particles. Moreover, the collision of solid particles with stirring structures is not conducive to the long-term use and maintenance of the equipment. The present application avoids the above problems by not adding solid particles.

[0057] To make a simple supplement to the background art to help understanding: In order to make the precursor formed by the reaction have better sphericity and reduce its agglomeration phenomenon as much as possible, the traditional method mostly controls the stirring intensity, and in combination with controlling the pH value of the reaction, so that the precursor obtains better sphericity. But in the actual chemical reaction process, due to the restriction of the structure of the reaction system, a large number of agglomerated particles are formed when the mixed salt solution, complexing agent, precipitating agent and other liquid materials initially nucleate. Due to the large number of soft agglomerates initially formed, the stirring action alone cannot achieve sufficient dispersion, and it is difficult to achieve the designed smaller nucleation particle size. When there are many agglomeration phenomena, multiple synthetic small balls will adhere and combine to form irregular large balls, resulting in an increase in large particles and a widening of the particle size distribution. In the battery, such agglomerated particles will hinder the transmission of lithium ions, thereby affecting the cycle performance of the positive electrode material, and ultimately restricting the performance of the battery.

[0058] Reference Figure 1 In the embodiment, the dispersion mechanism 4 includes an ultrasonic generator 41, a connecting line 42 and a dispersion rod 43 connected in sequence. The dispersion rod 43 is a component for dispersing and depolymerizing the reactants; In step four, the output power of the ultrasonic generator 41 is set to A; In step seven, the output power of the ultrasonic generator 41 is set to B; The A and the B satisfy: A = B.

[0059] The ultrasonic generator 41, the connecting line 42 and the dispersion rod 43 are existing devices, and the principle of combined use is not described here. In the working process, the dispersion rod 43 can prevent the formation of soft agglomerates during the synthesis process and can disperse the soft agglomerates after their formation by contacting the reactants.

[0060] In the embodiment, the output power of the ultrasonic generator 41 in different stages is the same. On the one hand, there is no need to frequently adjust the power in different stages, which reduces human operation errors (such as parameter setting errors and improper adjustment time), and is especially suitable for the scene of the embodiment which requires automation production degree and operation efficiency. On the other hand, frequent switching of the power of the ultrasonic generator 41 will cause the internal electronic components (such as power tubes and capacitors) to bear repeated current surges, which will shorten the service life of the equipment. Constant power operation can reduce such losses and prolong the stable working time of the equipment.

[0061] In the embodiment, the stirring part 2 is used to continuously stir the reactants in the reaction container 1 in steps one to eight.

[0062] The dispersion mechanism 4 only works in part of the time period, while the stirring member 2 stirs the raw materials in the whole time period of the reaction, controls the particle growth rate and morphology (such as avoiding agglomeration and maintaining sphericity) through a stable flow field environment, and ensures the consistency of the performance of the final product.

[0063] Referring to Figure 1 In the embodiment, the dispersion container 3 has a feeding port 31 and a discharging port 32, the feeding port 31 is arranged at the bottom end of the dispersion container 3, and the discharging port 32 is arranged at the top end of the dispersion container 3. In steps three and six, the reactants in the reaction container 1 are transferred into the dispersion container 3 through the feeding port 31. In steps five and eight, the reactants in the dispersion container 3 are transferred into the reaction container 1 through the discharging port 32.

[0064] The feeding port 31 is arranged at the bottom end of the dispersion container 3, and the discharging port 32 is arranged at the top end of the dispersion container 3, based on which, a flow path of feeding from the bottom and discharging from the top is formed, when feeding from the bottom, the reactants flow upward naturally under the action of the conveying pressure and the buoyancy, the path length and the residence time of the reactants in the dispersion container 3 are prolonged, and this embodiment is suitable for the scene that needs to be fully dispersed and depolymerized.

[0065] In some embodiments, along the radial direction of the dispersion container 3, the feeding port 31 and the discharging port 32 are arranged at the symmetrical two ends of the dispersion container 3.

[0066] Referring to Figure 1 In the embodiment, the preparation system further includes a first conveying pipe 5 and a flow meter 6. In steps five and eight, the reactants in the dispersion container 3 are transferred into the reaction container 1 through the first conveying pipe 5, and the flow in the first conveying pipe 5 is monitored through the flow meter 6.

[0067] The specific material and the like of the first conveying pipe 5 and the type of the flow meter 6 are not limited, as long as the above-mentioned purposes can be achieved.

[0068] The reactants in the dispersion container 3 are transferred into the reaction container 1 through the first conveying pipe 5, in addition, a pneumatic pump 10 can also be introduced, and the reactants are transferred through the pneumatic pump 10. The reactants in the reaction container 1 can also be transferred into the dispersion container 3 through the conveying pipe.

[0069] The flow monitoring arrangement is introduced in the embodiment to avoid that the residence time of the reactants in the dispersion container 3 is short due to that the flow when the reactants are transferred out is higher than the predetermined value, and the dispersion and depolymerization effect is guaranteed. The principle of the combination of the first conveying pipe 5 and the flow meter 6 is well known, and is not described here.

[0070] Referring to Figure 1In the embodiment, the preparation system further comprises a sampling member 7; In steps four and seven, the reactant in the dispersion container 3 is sampled by the sampling member 7, and then the sampling sample is detected, and the dispersion depolymerization setting of the dispersion mechanism 4 is adjusted according to the detection result.

[0071] The sampling member 7 can adopt an existing sampling ball valve. The sampling process of the sampling member 7 is not limited.

[0072] The sample detection method adopts an existing one, which is not limited. For example, a scanning electron microscope is adopted, the dispersion depolymerization effect is judged according to the scanning electron microscope photo, and then the dispersion depolymerization setting of the dispersion mechanism 4 is adjusted, such as adjusting the output power of the ultrasonic generator 41, to realize the closed-loop control logic of “sampling detection-result feedback-parameter adjustment”, and to guarantee the dispersion depolymerization effect.

[0073] Referring to Figure 1 In the embodiment, the preparation system further comprises a second material conveying pipe 8 and a moving base 9. In steps three and six, the reactant in the reaction container 1 is transferred into the dispersion container 3 through the second material conveying pipe 8. The dispersion container 3 is fixed on the top of the moving base 9, and the fluid flow path in the second material conveying pipe 8 is adjusted through the moving base 9.

[0074] The specific material and the like of the second material conveying pipe 8 are not limited.

[0075] The specific structure of the moving base 9 is not limited, but in this embodiment, the moving base 9 can include a base body 91 and a plurality of universal wheels 92 to form a moving trolley structure, so that it can be freely switched to be installed on other reaction containers 1, and can be used at any time, which is simple and convenient to operate, and is suitable for large-scale production.

[0076] The reactant in the reaction container 1 is transferred into the dispersion container 3 through the second material conveying pipe 8, and in addition, the following settings can be introduced: First, an electromagnetic valve 20 is installed on the reaction container 1 or the second material conveying pipe 8 to control the outflow process of the reactant. Second, the height of the reaction container 1 is higher than the height of the feeding port 31 on the dispersion container 3. Third, a conveying pump 30 is introduced to ensure that the reactant has enough power to enter the dispersion container 3.

[0077] If the second material conveying pipe 8 is spirally arranged, the fluid flow path in the second material conveying pipe 8 is a spiral path. Through the arrangement of the moving base 9, on the one hand, the dispersion container 3 and the dispersion mechanism 4 can be conveniently transferred, and on the other hand, the fluid flow path in the second material conveying pipe 8 can be conveniently adjusted, for example, the fluid flow path is a straight line, so as to guarantee the outflow rate of the reactant.

[0078] Referring to Figure 1 In the present embodiment, the dispersion container 3 comprises a corresponding assembled barrel 33 and cover 34, and part of the dispersion mechanism 4 is placed in the barrel 33. The preparation method further comprises: Step nine, after the secondary dispersion depolymerization treatment is completed, the barrel 33 and the cover 34 are separated, and the inner side wall part of the barrel 33, the inner side wall part of the cover 34, and the part of the dispersion mechanism 4 placed in the barrel 33 are cleaned.

[0079] The shape, assembly method, etc. of the barrel 33 and the cover 34 are not limited. The cover 34 can be opened to the above-mentioned part structure, which is not limited.

[0080] Part of the dispersion mechanism 4 is placed in the inner side of the barrel 33, for example, the dispersion rod 43 is placed in the inner side of the barrel 33.

[0081] After the secondary dispersion depolymerization treatment is completed, the reactants are returned to the reaction container 1, and the stirring treatment can be continued. Finally, the reactants are removed from the reaction container 1 and then continue to process the subsequent raw materials. By cleaning the inner side wall part of the barrel 33, the inner side wall part of the cover 34, and the part of the dispersion mechanism 4 placed in the inner side of the barrel 33, on the one hand, it can avoid the gradual damage of these structures due to the corrosive properties of the reactants, on the other hand, it can eliminate the interference of historical residues on the reaction system.

[0082] It should be noted that the reactants are gradually flowed into the dispersion container 3 and gradually flowed out of the dispersion container 3, and it is not necessary to temporarily store all the reactants in the dispersion container 3 and then discharge them as a whole. Based on this, the capacity of the dispersion container 3 can be much smaller than the capacity of the reaction container 1, and it is more necessary to clean the dispersion container 3. The cleaning of the reaction container 1 is not limited here.

[0083] Here, specific examples are provided for comparison with comparative examples: Example 1: The purpose is to prepare a ternary precursor with a nickel-cobalt-manganese ratio of 0.72:0.08:0.20; the metal solution used is a mixed salt solution composed of nickel sulfate, cobalt sulfate and manganese sulfate with a total concentration of 2±0.1 mol / L; the complexing agent is 5 mol / L ammonia water; the precipitating agent is 8 mol / L sodium hydroxide solution; the stirring speed is 250 rpm; the reaction temperature is 60℃, with a control accuracy of ±2℃; the ammonia content of the system is 0.30-0.35 mol / L, the pH value in the reaction container is controlled at 11.5-12.5, with a control accuracy of ±0.05; the frequency of the ultrasonic generator is set to 50KHZ; the flow rate of the reactants returned to the reaction container is 5 m³ / H; the co-precipitation reaction time is 80h, and after the reaction is completed, it is washed, dried, mixed, sieved, and iron is removed to obtain Figure 3a ternary precursor in the formula (Ni0.85Co0.10Mn0.05)3(PO4)2, the precursor having uniform morphology, good dispersibility, and no agglomeration morphology.

[0084] Example 2: A ternary precursor in the formula (Ni0.85Co0.10Mn0.05)3(PO4)2was prepared, the precursor having uniform morphology, good dispersibility, and no agglomeration morphology. Figure 4

[0085] Example 3: A ternary precursor in the formula (Ni0.90Co0.07Mn0.03)3(PO4)2was prepared, the precursor having uniform morphology, good dispersibility, and no agglomeration morphology. Figure 5

[0086] Example 4: A ternary precursor in the formula (Ni0.92Co0.06Mn0.02)3(PO4)2was prepared, the precursor having uniform morphology, good dispersibility, and no agglomeration morphology.​​Figure 6 The ternary precursor in the formula (I) has uniform morphology, good dispersibility and no agglomeration morphology.

[0087] Comparative Example 1: The purpose is to prepare a ternary precursor with a nickel-cobalt-manganese ratio of 0.72:0.08:0.20; the metal solution used is a mixed salt solution composed of nickel sulfate, cobalt sulfate and manganese sulfate, with a total concentration of 2±0.1 mol / L; the complexing agent is 5 mol / L ammonia water; the precipitating agent is 8 mol / L sodium hydroxide solution; the stirring speed is 250 rpm; the reaction temperature is 60℃, with a control accuracy of ±2℃; the ammonia content in the system is 0.30-0.35 mol / L; after starting the liquid feeding, the coprecipitation reaction is carried out normally without external circulation dispersion treatment, and the process monitoring morphology is seen in Figure 7 The morphology has poor dispersibility, and small particle agglomeration and adhesion are obvious; the coprecipitation reaction time is 80 h, and after the reaction is completed, the ternary precursor in the formula (I) is obtained after washing, drying, mixing, sieving and iron removal. Figure 8 The morphology has poor dispersibility, and small particle agglomeration and adhesion are obvious; the coprecipitation reaction time is 80 h, and after the reaction is completed, the ternary precursor in the formula (I) is obtained after washing, drying, mixing, sieving and iron removal.

[0088] After 1H of starting liquid feeding, the particle size is tested by using Mastersizer 2000, and the particle size and diameter distance changes of Comparative Example 1-4 and Comparative Example 1 can be seen (see Table 1), and the external circulation ultrasonic dispersion is more conducive to the dispersion of small particles and the formation of nucleation control small particles.

[0089] Table 1 Particle size comparison before and after external circulation dispersion Conditions D50 / pm Span Example 1 1.545 1.038 Example 2 1.616 1.059 Example 3 1.617 1.033 Example 4 1.450 1.061 Comparative Example 1 2.481 1.530 The above examples are only for illustrating the technical concept and characteristics of the present application, the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and it cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.

Claims

1. A method for preparing a ternary cathode material precursor, characterized in that: The preparation system includes a reaction vessel (1), a stirrer (2), a dispersion vessel (3), and a dispersion mechanism (4). Preparation methods include: Step 1: Input the raw materials into the reaction vessel (1), the raw materials including molten metal, complexing agent and precipitant; Step 2: Use the stirrer (2) to stir the raw materials in the reaction vessel (1) and monitor the reaction stage of the raw materials; Step 3: When the reaction is in the initial nucleation stage, the reactants in the reaction vessel (1) are gradually transferred into the dispersion vessel (3); Step 4: The reactants initially transferred into the dispersion container (3) are subjected to initial dispersion and depolymerization treatment through the dispersion mechanism (4) to achieve the purpose of nucleation. Step 5: During the initial dispersion and depolymerization process, the reactants in the dispersion container (3) are gradually transferred into the reaction container (1); Step 6: When the reaction stage enters the later growth stage, the reactants in the reaction vessel (1) are gradually transferred back into the dispersion vessel (3); Step 7: The reactants that are transferred back into the dispersion container (3) are subjected to secondary dispersion and depolymerization treatment by the dispersion mechanism (4) to promote the uniform dispersion of the reactants for co-precipitation reaction. Step 8: During the secondary dispersion and depolymerization process, the reactants in the dispersion container (3) are gradually transferred into the reaction container (1).

2. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: The dispersing mechanism (4) includes an ultrasonic generator (41), a connecting line (42), and a dispersing rod (43) connected in sequence. The dispersing rod (43) serves as a component for dispersing and depolymerizing the reactants; In step four, the output power of the ultrasonic generator (41) is set to A; In step seven, the output power of the ultrasonic generator (41) is set to B; A and B satisfy the condition: A = B.

3. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: In steps one through eight, the stirrer (2) is used to continuously stir the reactants in the reaction vessel (1).

4. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: The dispersion container (3) has a feed inlet (31) and a discharge outlet (32). The feed inlet (31) is located at the bottom of the dispersion container (3), and the discharge outlet (32) is located at the top of the dispersion container (3). In steps three and six, the reactants in the reaction vessel (1) are transferred into the dispersion vessel (3) through the feed inlet (31); In steps five and eight, the reactants in the dispersion container (3) are transferred into the reaction container (1) through the discharge port (32).

5. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: The preparation system also includes a first feed pipe (5) and a flow meter (6); In steps five and eight, the reactants in the dispersion container (3) are transferred into the reaction container (1) through the first feed pipe (5), and the flow rate in the first feed pipe (5) is monitored by the flow meter (6).

6. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: The preparation system also includes a sampling component (7). In steps four and seven, the reactants in the dispersion container (3) are sampled by the sampling device (7), and then the sampled samples are tested. The dispersion and depolymerization settings of the dispersion mechanism (4) are adjusted according to the test results.

7. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: The preparation system also includes a second material delivery pipe (8) and a movable base (9); In steps three and six, the reactants in the reaction vessel (1) are transferred into the dispersion vessel (3) through the second feed pipe (8); The dispersion container (3) is fixedly mounted on the top of the movable base (9), and the fluid flow path in the second conveying pipe (8) is adjusted by the movable base (9).

8. The method for preparing a ternary cathode material precursor according to claim 1, characterized in that: The dispersion container (3) includes a correspondingly assembled cylinder (33) and a cover (34), and part of the dispersion mechanism (4) is placed inside the cylinder (33); The preparation method also includes: Step 9: After the secondary dispersion and deagglomeration process is completed, separate the cylinder (33) and the cover (34), and clean the inner wall of the cylinder (33), the inner wall of the cover (34), and the part of the dispersion mechanism (4) placed inside the cylinder (33).

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