Reaction kettle for preparing ternary positive electrode material precursor and preparation method thereof

Abstract

This invention discloses a standby reactor for preparing a ternary cathode material precursor, comprising: a reactor body, an end cap detachably connected to the reactor body; a stirring device, comprising: a stirring shaft extending axially, one end of which is fixedly connected to the end cap; a first stirring paddle fixedly connected to the other end of the stirring shaft; a second stirring paddle sleeved on the outer periphery of the stirring shaft and positioned axially between the first stirring paddle and the end cap; and a displacement assembly for driving the second stirring paddle to move axially. This invention can adjust the axial position of the second stirring paddle in real time according to the dynamic changes in the liquid level within the reactor, effectively improving the mass transfer effect and turbulent kinetic energy distribution within the reactor, and enhancing the sphericity and particle size uniformity of the prepared ternary cathode material precursor. This invention also discloses a method for preparing a ternary cathode material precursor.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a standby reactor for a ternary cathode material precursor system and a method for preparing a ternary cathode material precursor. Background Technology

[0002] Solid-state sintering is a commonly used technique in the preparation of ternary cathode materials. This method involves mixing a ternary cathode material precursor with a lithium salt and calcining it at high temperature in a pure oxygen atmosphere to form the ternary cathode material. Extensive experimental studies and literature indicate that the sintered ternary cathode material exhibits a significant "inheritance" of the physical and chemical properties of its precursor. Therefore, the quality of the ternary cathode material precursor is a key factor determining the electrochemical performance of the final ternary cathode material.

[0003] In the industrial preparation of ternary cathode material precursors, the continuous stirred reactor (CSTR) system has become the most widely adopted preparation system by manufacturers due to its advantages of high repeatability, high reliability, and scale-up potential. The principle of the CSTR system is to achieve uniform deposition of multiple transition metal elements through co-precipitation reactions. Simultaneously, these nanoscale deposited particles (primary particles) self-assemble into secondary spheres of approximately 10 micrometers. Therefore, this system requires not only good mass transfer to ensure uniform dispersion of the transition metals within the reactor, but also uniform distribution of turbulent kinetic energy to avoid affecting the sphericity and particle size uniformity of the secondary spheres.

[0004] To address the aforementioned issues, existing technologies typically employ multiple coaxial stirring paddles fixedly mounted in the reactor. However, the preparation of ternary cathode material precursors is characterized by dynamic changes in the liquid level within the reactor, slow feed rates, and long reaction times. This makes the aforementioned stirring structures unsuitable for actual preparation requirements: when the liquid level is low, the higher-positioned stirring paddles cannot effectively perform their stirring function; and in the later stages of the reaction, the liquid level rises significantly, submerging all stirring paddles. Because the stirring paddles are fixed in position and cannot be moved or adjusted, a stirring "dead zone" appears within the reactor, resulting in uneven distribution of turbulent kinetic energy. This severely affects the sphericity and uniformity of the prepared ternary cathode material precursor. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention discloses a standby reactor for a ternary cathode material precursor system and a method for preparing a ternary cathode material precursor.

[0006] In a first aspect, embodiments of the present invention provide a standby reactor for a ternary cathode material precursor system, comprising:

[0007] The vessel body,

[0008] The end cap is detachably connected to the vessel body;

[0009] A stirring device, comprising:

[0010] A stirring shaft extends axially, with one end fixedly connected to the end cap.

[0011] The first stirring paddle is fixedly connected to the other end of the stirring shaft;

[0012] The second stirring blade is sleeved on the outer periphery of the stirring shaft and is located between the first stirring blade and the end cap along the axial direction.

[0013] A displacement component is used to drive the second stirring paddle to move along the axial direction.

[0014] By adopting the above technical solution, the present invention effectively improves the mass transfer effect and turbulent kinetic energy distribution in the reactor through the synergistic effect of a fixed first stirring impeller, an axially adjustable second stirring impeller, and a displacement component for driving the second stirring impeller to move, thereby enhancing the sphericity and particle size uniformity of the prepared ternary cathode material precursor.

[0015] Optionally, the end cap is provided with an air inlet, the stirring shaft has a hollow structure, one end of the stirring shaft is connected to the air inlet, and the side wall of the stirring shaft is provided with an air outlet. External gas enters the hollow structure of the stirring shaft through the air inlet and flows out into the interior of the vessel through the air outlet.

[0016] Optionally, the first stirring impeller includes a first stirring blade and a first elastic layer, and the second stirring impeller includes a second stirring blade and a second elastic layer, wherein the first elastic layer covers the surface of the first stirring blade and the second elastic layer covers the surface of the second stirring blade.

[0017] Optionally, the first impeller is a turbine impeller, and the second impeller is a propeller impeller or a paddle impeller.

[0018] Optionally, the displacement component includes:

[0019] A drive motor is provided, and one end of the stirring shaft is fixedly connected to the end cover via the drive motor.

[0020] A take-up pulley is located on the output shaft of the drive motor;

[0021] A drive belt extends along the axial direction, one end of which is connected to the take-up pulley and the other end is connected to the second stirring paddle.

[0022] The drive motor drives the output shaft of the drive motor to rotate, which in turn drives the take-up pulley to rotate to wind or unwind the transmission belt, thereby driving the second stirring paddle to move along the axial direction.

[0023] In a second aspect, embodiments of the present invention provide a method for preparing a ternary cathode material precursor, using a reaction vessel as described in any embodiment of the first aspect, wherein the axial distance between the first stirring impeller and the bottom of the vessel is 1 / 5 to 1 / 4 of the height of the vessel, and the preparation method includes:

[0024] Feeding steps: Start the first and second stirring paddles to stir. While stirring, introduce a nickel-cobalt-manganese salt solution with a metal ion concentration of 1.5~3.0 mol / L and a complexing agent with a concentration of 1.2~3.6 mol / L into the reactor at the same rate. Then, introduce a precipitant with a concentration of 1.5~3.0 mol / L to control the pH of the solution in the reactor to 10~12, thereby obtaining the ternary cathode material precursor.

[0025] Specifically, when the liquid level in the reactor is lower than 1 / 10 to 1 / 8 of the height of the reactor body, the position of the second stirring paddle is controlled so that the axial distance between the second stirring paddle and the first stirring paddle is less than 1 / 5 to 1 / 4 of the height of the reactor body; when the liquid level in the reactor reaches 1 / 10 to 1 / 8 or more of the height of the reactor body, the position of the second stirring paddle is controlled so that the difference between the liquid level in the reactor and the axial height of the second stirring paddle is maintained at 1 / 10 to 1 / 4 of the height of the reactor body.

[0026] By adopting the above technical solution and through the synergistic effect of the above reaction vessel and process parameters, a ternary cathode material precursor with uniformity, high sphericity and high tap density is prepared.

[0027] Optionally, the moving speed of the second stirring paddle is 2 / 3 to 3 / 4 of the speed at which the liquid level rises in the reactor.

[0028] Optionally, the stirring speed of both the first and second stirring paddles is 600~1000 rpm.

[0029] Optionally, the end cap is provided with an air inlet, the stirring shaft has a hollow structure, one end of the stirring shaft is connected to the air inlet, and the side wall of the stirring shaft is provided with an air outlet.

[0030] The process includes a pretreatment step before the feeding step, wherein the temperature of the reactor is controlled at 40~60℃, nitrogen gas is introduced into the hollow structure of the stirring shaft through the air inlet and flows out into the reactor body through the air outlet, and then a 0.4~1.2mol / L ammonia solution is introduced into the reactor.

[0031] Optionally, after the feeding step, there are also aging, washing and drying steps, in which the solution in the reactor is aged for 9-10 hours, followed by washing and drying to obtain the ternary cathode material precursor. Attached Figure Description

[0032] Figure 1 A schematic diagram of the structure of the reaction vessel in an embodiment of the present invention is shown;

[0033] Figure 2 A scanning electron microscope (SEM) image of the ternary cathode material precursor prepared in Example 1 is shown. Figure 1 ;

[0034] Figure 3 A scanning electron microscope (SEM) image of the ternary cathode material precursor prepared in Example 1 is shown. Figure 2 ;

[0035] Figure 4 The scanning electron microscope image shows the preparation of the ternary cathode material precursor in Comparative Example 1. Figure 1 ;

[0036] Figure 5 The scanning electron microscope image shows the preparation of the ternary cathode material precursor in Comparative Example 1. Figure 2 ;

[0037] Figure 6 The diagram shows the state inside the reactor when the distance between the second stirring paddle and the bottom of the reactor body during the preparation process of Example 1 is 9 / 20, 14 / 20 and 19 / 20 of the reactor body height, respectively;

[0038] Figure 7 The diagram shows the state inside the reactor when the distance between the second fixed stirring paddle and the bottom of the reactor is 1 / 2 of the reactor height at three different liquid levels during the preparation process in Comparative Example 1.

[0039] Figure 8 This shows the reaction vessel in Example 1 obtained using Fluent software. Figure 6 The simulation results of the flow field linear velocity distribution under the three liquid level conditions are shown in the figure.

[0040] Figure 9 This shows the reaction vessel in Comparative Example 1 obtained using Fluent software. Figure 7 The simulation results of the flow field linear velocity distribution under the three liquid level conditions are shown in the figure.

[0041] Figure 10 The diagram shows a comparison of the dispersion efficiency of the liquid in the reactor when the feed is 5 seconds old in Example 1 and Comparative Example 1.

[0042] Figure 11 A comparison diagram of particle size distribution between Example 1 and Comparative Example 1 is shown.

[0043] (Symbol Explanation)

[0044] 1. Vessel body; 2. Stirring device; 21. Stirring shaft; 22. First stirring paddle; 23. Second stirring paddle; 24. Displacement assembly; 241. Drive motor; 242. Belt take-up pulley; 243. Transmission belt. Detailed Implementation

[0045] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to these embodiments. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a deep understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0046] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0047] The terms “first”, “second”, etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0048] In the description of this embodiment, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment based on the specific circumstances.

[0049] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0050] Firstly, reference Figure 1 As shown, an embodiment of the present invention provides a standby reactor for a ternary cathode material precursor system, including a reactor body 1, an end cap (not shown) and a stirring device 2, wherein the end cap is detachably connected to the reactor body 1.

[0051] The stirring device 2 includes a stirring shaft 21, a first stirring blade 22, and a second stirring blade 23. The stirring shaft 21 is axial (e.g., along the axial direction). Figure 1 Extending in the direction shown (x), one end of the stirring shaft 21 is fixedly connected to the end cap, and the other end of the stirring shaft 21 is fixedly connected to the first stirring paddle 22. The second stirring paddle 23 is sleeved on the outer periphery of the stirring shaft 21, and the second stirring paddle 23 is located axially between the first stirring paddle 22 and the end cap. The displacement assembly 24 is used to drive the second stirring paddle 23 to move axially.

[0052] Specifically, the ternary cathode material precursor is prepared by a co-precipitation reaction of a metal salt solution, a complexing agent, and a precipitant in a reactor. "Co-precipitation" refers to the process in which multiple metal ions in the metal salt solution can simultaneously undergo precipitation reactions. In this preparation process, if the metal salt solution, complexing agent, and precipitant are fed into the reactor all at once—that is, a feeding method that maintains a fixed liquid level in the reactor during the feeding process—different metal ions in the metal salt solution are prone to stepwise precipitation, ultimately resulting in an uneven composition of the precursor. To solve this problem, a method of feeding the metal salt solution, complexing agent, and precipitant sequentially is typically used. This feeding method results in a dynamic change in the liquid level within the reactor during the feeding process.

[0053] Based on this, the present invention fixes the first stirring paddle 22 at the end of the stirring shaft 21 away from the end cap, and the second stirring paddle 23 is movably sleeved on the outer periphery of the stirring shaft 21 and located between the first stirring paddle 22 and the end cap. Simultaneously, a displacement component 24 is configured to drive the second stirring paddle 23 to move axially along the stirring shaft 21, achieving flexible adjustment of the axial position of the second stirring paddle 23. This adapts to the dynamic changes in the liquid level within the reactor during the preparation of the ternary cathode material precursor. The axial position of the second stirring paddle 23 can be adjusted in real time according to the dynamic changes in the liquid level within the reactor, effectively avoiding the problems of the upper stirring paddles failing to perform their stirring function when the liquid level is low in the early stages of preparation, and the formation of a stirring dead zone within the reactor after the liquid level rises and submerges all the stirring paddles in the later stages of preparation. This allows the stirring paddles to effectively and comprehensively stir the reaction system with dynamically changing liquid levels within the reactor, thereby eliminating the mixing "dead zone" within the reactor and promoting the uniform distribution of turbulent kinetic energy, effectively improving the sphericity and particle size uniformity of the prepared ternary cathode material precursor.

[0054] By adopting the above technical solution, the present invention effectively improves the mass transfer effect and turbulent kinetic energy distribution in the reactor through the synergistic effect of a fixed first stirring paddle 22, an axially adjustable second stirring paddle 23, and a displacement component 24 for driving the second stirring paddle to move, thereby enhancing the sphericity and particle size uniformity of the prepared ternary cathode material precursor.

[0055] In some embodiments of the present invention, the displacement component 24 is used to drive the second stirring paddle 23 to move axially from an initial position, wherein the initial position is such that the axial distance between the second stirring paddle 23 and the first stirring paddle 22 is less than or equal to the axial distance between the first stirring paddle 22 and the bottom of the vessel 1.

[0056] In the above embodiment, this arrangement allows the second stirring paddle 23 and the first stirring paddle 22 to form close-range synergistic stirring when the liquid level in the reactor is low in the early stage of preparation. This fully covers the low-level liquid phase reaction area in the reactor, further preventing the second stirring paddle 23 from failing to perform its stirring function due to excessive distance between the two paddles. Simultaneously, the initial position limitation provides sufficient adjustment space for the second stirring paddle 23 to move upwards along the axial direction to accommodate the gradual increase in the liquid level in the reactor, allowing the second stirring paddle 23 to adjust its position synchronously with the rise in liquid level. This, combined with the first stirring paddle 22, achieves stratified, full-coverage stirring under different liquid level conditions in the reactor, further avoiding dead zones in the reactor during the liquid level rise process. This further ensures the uniformity of mass transfer and turbulent kinetic energy distribution of materials in the reactor during preparation, improving the sphericity and particle size uniformity of the prepared precursor.

[0057] Furthermore, the axial distance between the first stirring impeller 22 and the bottom of the vessel body 1 is 1 / 5 to 1 / 4 of the height of the vessel body 1. This effectively avoids structural interference between the stirring impeller and the bottom of the vessel body 1, while fully utilizing the stirring action to efficiently stir the material at the bottom of the vessel body 1, further avoiding mixing dead zones at the bottom of the vessel body 1. Simultaneously, this spacing allows the first stirring impeller 22 to effectively stir the liquid phase material in the reactor even when the liquid level is low in the early stages of preparation. This further ensures the uniformity of mass transfer and turbulent kinetic energy distribution within the reactor, guaranteeing the stability of crystal nucleus generation and growth in the initial stage of the reaction, and providing a solid foundation for improving the overall uniformity of the ternary cathode material precursor.

[0058] In some embodiments of the present invention, the end cap is provided with an air inlet, the stirring shaft 21 has a hollow structure, one end of the stirring shaft 21 is connected to the air inlet, and the side wall of the stirring shaft 21 is provided with an air outlet. External gas enters the hollow structure of the stirring shaft 21 through the air inlet and flows out into the interior of the vessel body 1 through the air outlet. Exemplarily, the external gas is, for example, an inert gas.

[0059] In the above embodiment, external gas enters the hollow structure of the stirring shaft 21 through the air inlet and flows out into the reactor body 1 through the air outlet. Utilizing the turbulent state of the materials inside the reactor during stirring, the gas forms microbubbles in the liquid phase system and diffuses uniformly. Simultaneously, this design provides the necessary gas environment for the stable reaction system according to the process requirements of the co-precipitation reaction of the ternary cathode material precursor, effectively avoiding localized differences in the reaction environment caused by uneven gas distribution. This ensures the consistency of the reaction process in each area of ​​the reactor, thereby reducing differences in precursor particle nucleation and growth caused by uneven reaction environments, and further improving the compositional uniformity, sphericity, and particle size uniformity of the ternary cathode material precursor. Furthermore, this integrated structural design simplifies the overall layout of the reactor, eliminating the need for an additional independent air inlet device, reducing the complexity of the equipment structure, and improving the stability and practicality of the equipment operation.

[0060] In some other embodiments of the present invention, the first stirring paddle 22 includes a first stirring blade and a first elastic layer, and the second stirring paddle 23 includes a second stirring blade and a second elastic layer, wherein the first elastic layer covers the surface of the first stirring blade and the second elastic layer covers the surface of the second stirring blade.

[0061] In the above embodiments, by coating the surface of the first stirring blade with a first elastic layer and the surface of the second stirring blade with a second elastic layer, the flexibility of the first and second elastic layers can buffer the direct contact and collision between the stirring blade and the precursor crystal nucleus during the rotation of the stirring blade. This effectively weakens the shear impact force generated by the rigid contact of the stirring blade, avoids morphological damage to the ternary cathode material precursor crystal nucleus caused by the rigid blade, and ensures the spherical growth state of the ternary cathode material precursor crystal nucleus. At the same time, the first and second elastic layers can soften the flow field boundary layer on the surface of the stirring blade, eliminate the local high-speed shear flow that is easily formed on the surface of the rigid blade, improve the uniformity of turbulent kinetic energy distribution in the reactor, reduce the difference in the growth rate of the ternary cathode material precursor crystal nucleus caused by local shear flow, and improve the particle size and composition uniformity of the ternary cathode material precursor. In addition, the low surface energy of the first and second elastic layers can reduce the adhesion of the ternary cathode material precursor to the surfaces of the first and second stirring blades, respectively, and prevent the material from adhering and agglomerating on the blade surfaces to form large particulate impurities, thereby further ensuring the purity and morphological consistency of the ternary cathode material precursor preparation.

[0062] Furthermore, both the first stirring impeller 22 and the second stirring impeller 23 are one type of turbine stirring impeller, propeller stirring impeller, and paddle stirring impeller. This not only helps to eliminate the stirring dead zone in the reactor, but also allows for control of the stirring shear intensity according to the crystal nucleus growth characteristics, avoiding damage to the spherical morphology of the precursor crystal nuclei by shearing action, thereby ensuring the sphericity, particle size, and compositional uniformity of the ternary cathode material precursor. In this embodiment, the first stirring impeller 22 and the second stirring impeller 23 can be the same type of stirring impeller, or they can be different types of stirring impellers.

[0063] Preferably, the first impeller 22 is a turbine impeller, and the second impeller 23 is a propeller impeller or a paddle impeller. Thus, by utilizing the excellent radial shearing capability of the turbine impeller and the strong axial conveying characteristics of the propeller impeller or paddle impeller, a flow field distribution of "high shear at the bottom and large circulation at the top" is constructed within the reactor. This combination enables the first impeller 22, located at the bottom of the reactor body 1, to efficiently disperse and rapidly mix the mixture within the reactor, preventing excessively high local concentrations that could lead to spontaneous nucleation or component segregation. Meanwhile, the second impeller 23, located at the top, promotes axial circulation between the mixture at the bottom and top of the reactor body 1, eliminating mixing dead zones.

[0064] In other words, the first impeller 22 and the second impeller 23 use different types of impellers, and the impellers as described above can significantly optimize the turbulence distribution in the reactor. This not only enhances the mass transfer efficiency in the reactor and ensures the uniformity of temperature, pH value and concentration of the reaction system, but also provides a suitable environment for precursor crystal growth. It effectively reduces crystal breakage caused by excessive local shear force or widening of particle size distribution caused by uneven mixing, thereby ultimately improving the sphericity, tap density and consistency of the ternary cathode material precursor product.

[0065] In some embodiments of the present invention, the displacement component includes:

[0066] Drive motor 241, one end of stirring shaft 21 is fixedly connected to end cover via drive motor 241;

[0067] The take-up pulley 242 is located on the output shaft of the drive motor 241;

[0068] The drive belt 243 extends axially, with one end connected to the take-up pulley 242 and the other end connected to the second stirring paddle 23.

[0069] The drive motor 241 drives its output shaft to rotate, which in turn drives the take-up pulley 242 to rotate to wind or release the transmission belt 243, thereby driving the second stirring paddle 23 to move axially.

[0070] In the above embodiment, the output shaft is driven by the drive motor 241 to rotate, which in turn drives the take-up pulley 242 to rotate. This, in turn, achieves the axial lifting and lowering movement of the second stirring paddle 23 through the winding or releasing of the transmission belt 243. This mechanical transmission structure is compact and offers high control precision, enabling the second stirring paddle 23 to quickly adjust to the optimal stirring position based on dynamic changes in the liquid level within the reactor. Furthermore, the flexible transmission characteristics of the transmission belt 243 effectively buffer the mechanical impact during displacement adjustment, preventing localized shear flow caused by sudden displacement changes in the second stirring paddle 23 and protecting the spherical growth state of the precursor crystal nuclei. In addition, the drive motor 241 is integrated into the end cap side, away from the reaction area inside the reactor. This facilitates equipment installation, maintenance, and repair, and also prevents corrosion of the transmission components by the reaction medium inside the reactor, improving the operational stability and service life of the displacement assembly 24.

[0071] Secondly, embodiments of the present invention provide a method for preparing a ternary cathode material precursor, using a reactor as described in any embodiment of the first aspect, wherein the axial distance between the first stirring paddle 22 and the bottom of the reactor body 1 is 1 / 5 to 1 / 4 of the height of the reactor body 1, and the preparation method includes:

[0072] Feeding steps: Start the first agitator 22 and the second agitator 23 to stir. Under stirring conditions, a nickel-cobalt-manganese salt solution with a metal ion concentration of 1.5~3.0 mol / L and a complexing agent with a concentration of 1.2~3.6 mol / L are introduced into the reactor at the same rate. Then, a precipitant with a concentration of 1.5~3.0 mol / L is introduced to control the pH value of the solution in the reactor to 10~12, thereby obtaining the ternary cathode material precursor.

[0073] Specifically, when the liquid level in the reactor is lower than 1 / 10 to 1 / 8 of the height of the reactor body, the position of the second stirring paddle 23 is controlled so that the axial distance between the second stirring paddle 23 and the first stirring paddle 22 is less than 1 / 5 to 1 / 4 of the height of the reactor body 1; when the liquid level in the reactor reaches 1 / 10 to 1 / 8 or more of the height of the reactor body 1, the position of the second stirring paddle 23 is controlled so that the difference between the liquid level in the reactor and the axial height of the second stirring paddle 23 is maintained at 1 / 10 to 1 / 4 of the height of the reactor body 1.

[0074] Specifically, with the first impeller 22 and the second impeller 23 stirring, this invention uses a nickel-cobalt-manganese salt solution with a metal ion concentration of 1.5~3.0 mol / L to feed into the reactor. This avoids the problems of explosive nucleation caused by excessively high metal ion concentration or slow nucleation caused by excessively low metal ion concentration. Furthermore, by controlling the concentration of the complexing agent to 1.2~3.6 mol / L and controlling the nickel-cobalt-manganese salt solution and the complexing agent to be fed at the same rate—that is, the nickel-cobalt-manganese salt solution and the complexing agent continuously and stably entering the reactor at the aforementioned constant molar ratio—the complexation equilibrium within the system remains stable, thereby achieving uniform complexation of the three metal ions.

[0075] Subsequently, a precipitant with a concentration of 1.5–3.0 mol / L is added to adjust the pH of the solution in the reactor to 10–12. This serves two purposes: firstly, it avoids insufficient anions per unit volume of precipitant when the concentration is too low. To maintain a pH of 10–12, the feed rate needs to be significantly increased, which can lead to excessive pH fluctuations during feeding, intermittent precipitation reactions, and irregular precursor particle morphology; simultaneously, insufficient local anion concentration results in slow crystal growth. Secondly, it avoids excessively high precipitant concentrations, as this can create a highly alkaline microenvironment when the precipitant comes into contact with the nickel-cobalt-manganese salt solution and the complexing agent mixture, leading to selective precipitation of metal ions. Therefore, by using the precipitant concentration described above, the precipitation rate of metal ions can be controlled, thereby achieving simultaneous precipitation of the three metal ions.

[0076] Furthermore, during the feeding process, by limiting the distance between the first stirring paddle 22 and the bottom of the vessel 1 to 1 / 5 to 1 / 4 of the height of the vessel 1, on the one hand, when the liquid level in the vessel 1 reaches or exceeds the position of the first stirring paddle 22, this distance can effectively enhance the fluid turbulence intensity at the bottom of the reactor and prevent local sedimentation of the liquid at the bottom of the vessel; on the other hand, when the liquid level in the vessel 1 does not reach the position of the first stirring paddle 22 (i.e., the first stirring paddle 22 is exposed above the liquid surface), this distance causes the rotation of the first stirring paddle 22 to drive the surrounding gas into a local airflow. When this airflow comes into contact with the liquid surface, it will generate a downward airflow thrust and tangential shear force on the liquid surface, thereby promoting the mixing of the liquid.

[0077] Simultaneously, the present invention can control the axial position of the second stirring paddle 23 according to the dynamic change of the liquid level height inside the reactor. Specifically, when the liquid level height is lower than 1 / 10 to 1 / 8 of the reactor body height, the distance between the second stirring paddle 23 and the first stirring paddle 22 is controlled to be less than 1 / 5 to 1 / 4 of the reactor body height. That is, when the second stirring paddle 23 is in its initial position, the distance between the second stirring paddle 23 and the first stirring paddle 22 is less than 1 / 5 to 1 / 4 of the reactor body height. For example, the distance between the second stirring paddle 23 and the first stirring paddle 22 is less than 1 / 5 of the reactor body height, less than 9 / 40 of the reactor body height, or less than 1 / 4 of the reactor body height. Preferably, the distance between the second stirring paddle 23 and the first stirring paddle 22 is 1 / 10 to 3 / 20 of the reactor body height. This configuration avoids interference between the second stirring paddle 23 and the rotation of the first stirring paddle 22, while enhancing airflow turbulence to further promote mixing of the liquid.

[0078] When the liquid level in the reactor reaches 1 / 10 to 1 / 8 or more of the height of the reactor body 1, the second stirring paddle 23 is moved axially (e.g., raised or lowered) to maintain the axial height difference between the second stirring paddle 23 and the liquid surface at 1 / 10 to 1 / 4 of the height of the reactor body 1. By controlling a specific distance between the second stirring paddle 23 and the liquid surface, it avoids the second stirring paddle 23 being unable to perform its stirring function when exposed above the liquid surface and far from it, and also prevents the formation of a stirring "dead zone" as the liquid level rises when the second stirring paddle 23 is below the liquid surface. Therefore, uniform turbulent kinetic energy distribution can be achieved in the reactor at different liquid level stages, and a uniform ternary cathode material precursor with high sphericity can be prepared.

[0079] By adopting the above technical solution and through the synergistic effect of the above reaction vessel and process parameters, a ternary cathode material precursor with uniformity, high sphericity and high tap density can be prepared.

[0080] In the above embodiments, for example, a nickel-cobalt-manganese salt solution with a metal ion concentration of 1.5~3.0 mol / L is prepared by dissolving nickel salt, cobalt salt, and manganese salt in water at a molar ratio of Ni:Co:Mn = (80~99):(1~20):(1~20). By adjusting the ratio of nickel salt, cobalt salt, and manganese salt, the high capacity requirements of ternary cathode materials can be further met.

[0081] For example, the complexing agent is ammonia, and the precipitant is NaOH or Na₂CO₃. This invention selects ammonia as the complexing agent, utilizing its ability to form soluble ammonia complexes with nickel, cobalt, and manganese metal ions. This effectively controls the concentration of free metal ions in the reaction system, thereby adjusting the supersaturation of the solution and avoiding explosive nucleation caused by excessively fast reaction rates, ensuring a stable and orderly crystal growth process. Simultaneously, the formation of ammonia complex ions reduces the Gibbs free energy of the reaction system, altering the relative growth rate of crystal faces, which is beneficial for exposing highly active crystal faces and improving the rate performance of the material. Furthermore, by selecting NaOH or Na₂CO₃ as the precipitant, the high concentration of hydroxide or carbonate ions provided by both can rapidly combine with the metal ions released from the complexation equilibrium to undergo a co-precipitation reaction.

[0082] As another example, the stirring speed of both the first stirring impeller 22 and the second stirring impeller 23 is 600~1000 rpm. Using a stirring speed within this range can provide suitable turbulent shear force and mixing ability, further ensuring the uniformity of the particle size distribution of the obtained ternary cathode material precursor.

[0083] Furthermore, a pretreatment step is included before the feeding step. This involves controlling the temperature of the reactor to 40-60°C, introducing nitrogen gas through the inlet into the hollow structure of the stirring shaft 21, and then allowing it to flow out through the outlet into the reactor body 1. Finally, a 0.4-1.2 mol / L ammonia solution is introduced into the reactor. Nitrogen gas serves as a protective gas, and the ammonia solution serves as the reaction base liquid.

[0084] By controlling the temperature of the reactor at 40-60℃ and using nitrogen gas as a protective gas through a hollow stirring shaft 21, dissolved oxygen in the reactor and feed solution can be effectively removed, preventing metal ions from being oxidized in the early stage of the reaction to generate high-valence impurities that are difficult to eliminate. Simultaneously, the adverse interference of oxygen on the kinetics of the co-precipitation reaction and crystal growth is eliminated. Based on this, the present invention introduces an ammonia solution of a specific concentration as the reaction base liquid into the reactor, pre-constructing a complexation reaction environment containing free ammonia ions within the reactor. This allows the reaction system to reach complexation equilibrium in the initial stage. This not only buffers the impact of high-concentration metal salt solution in the early stage of feeding and suppresses explosive nucleation caused by excessive instantaneous supersaturation, but also ensures that the ternary cathode material precursor crystal nuclei grow stably under mild conditions, thereby further obtaining a ternary cathode material precursor with high crystallinity, good sphericity, and uniform composition.

[0085] Furthermore, the process includes aging, washing, and drying steps after the feeding step. The solution in the reactor is aged for 9-10 hours, followed by washing and drying to obtain the ternary cathode material precursor. In this embodiment, "aging" refers to the process of allowing the precursor suspension in the reactor to remain in the original process environment (e.g., temperature, pH) after the feeding is completed.

[0086] By aging the solution in the reactor for 9-10 hours after the feeding step, the reaction system remains in a relatively static thermodynamic environment after the feeding is stopped. This process promotes Ostwald ripening of the precursor particles, where small-diameter crystals dissolve and redeposit on the surface of larger particles. This effectively eliminates lattice defects and internal stresses within the crystals, resulting in more complete and dense crystallization. Simultaneously, it ensures that residual nickel, cobalt, and manganese ions are completely precipitated under supersaturation, improving product yield and the accuracy of stoichiometry. The subsequent washing step effectively removes impurity ions adsorbed on the particle surface and in the interstices, preventing impurities from negatively impacting the subsequent sintering lattice formation and electrochemical performance of the cathode material. Furthermore, the drying step further removes moisture, preventing changes in surface properties during storage or transportation, ultimately yielding a high-purity, highly crystallized, and clean ternary cathode material precursor.

[0087] In some embodiments of the present invention, the moving speed of the second stirring paddle 23 is 2 / 3 to 3 / 4 of the rising speed of the liquid level in the reactor. Thus, by controlling the moving speed, disturbances or mechanical losses to the stable flow field caused by the second stirring paddle 23 moving too fast are avoided, as are insufficient upper-layer stirring caused by moving too slowly. This achieves a smooth transition and homogenization of the flow field from the bottom to the top of the reactor throughout the reaction process, further enhancing the mass transfer effect of the reactor and thus further ensuring the uniform growth and high sphericity of the ternary cathode material precursor particles. For example, the moving speed of the second stirring paddle 23 is 0.20 to 0.50 mm / min.

[0088] The following will describe the implementation method in more detail.

[0089] Example 1

[0090] The reaction vessel of the present invention is used, wherein the axial distance between the first stirring paddle 22 and the bottom of the vessel body 1 is 1 / 5 of the height of the vessel body 1, and the preparation method includes:

[0091] Pretreatment steps: The temperature of the reactor is controlled at 50℃. Nitrogen gas is introduced into the hollow structure of the stirring shaft 21 through the inlet and flows out into the reactor body 1 through the outlet. Then, a 0.4~1.2mol / L ammonia solution is introduced into the reactor. Nitrogen gas is used as a protective gas, and ammonia solution is used as the reaction base liquid.

[0092] Feeding procedure: Start the first stirring paddle 22 and the second stirring paddle 23 for stirring. The stirring speed of the first stirring paddle 22 and the second stirring paddle 23 is 600 rpm. Under stirring conditions, a nickel-cobalt-manganese salt solution with a metal ion concentration of 2.0 mol / L and an ammonia solution with a concentration of 1.2~3.6 mol / L are introduced into the reactor at a rate of 0.5 mL / min. Then, a 3.0 mol / L NaOH solution is introduced to control the pH value of the solution in the reactor to 10.5±0.01.

[0093] Specifically, when the liquid level in the reactor is lower than 1 / 10 to 1 / 8 of the height of the reactor body, the position of the second stirring paddle 23 is controlled so that the axial distance between the second stirring paddle 23 and the first stirring paddle 22 is less than 1 / 5 of the height of the reactor body 1; when the liquid level in the reactor reaches 1 / 10 to 1 / 8 or more of the height of the reactor body 1, the moving speed of the second stirring paddle 23 is 0.005 mm / min, and the position of the second stirring paddle 23 is controlled so that the difference between the liquid level in the reactor and the axial height of the second stirring paddle 23 is maintained at 1 / 10 to 1 / 4 of the height of the reactor body 1.

[0094] Aging, washing and drying steps: The solution in the reactor is aged for 10 hours, followed by washing and drying to obtain the ternary cathode material precursor.

[0095] In Example 1, a ternary cathode material precursor was prepared as follows: Figure 2 and Figure 3 As shown in the diagram, the distances between the second stirring paddle and the bottom of vessel 1 at three different liquid levels during the preparation process are 9 / 20, 14 / 20, and 19 / 20 of the height of vessel 1, respectively. Figure 6 As shown, "H" represents the height of vessel 1. The reactor was analyzed using Fluent software. Figure 6 The flow field linear velocity distribution under the three liquid level states shown was simulated, and the simulation results are as follows: Figure 8 As shown. Figure 8 In this context, "Volume fraction of liquid" refers to the volume fraction of the liquid, and "initial state" refers to the initial state as shown in the image. Figure 6 The liquid volume fraction distribution in the reactor before stirring under three liquid levels and corresponding positions of the second agitator 23. "Final state" indicates the state at which the liquid volume fraction distribution in the reactor is before stirring. Figure 6 The liquid volume fraction distribution in the reactor during stirring is shown under three liquid levels and the corresponding positions of the second stirring paddle 23. "Linear velocity distribution" indicates the distribution of liquid volume fraction within the reactor during stirring. Figure 6 The linear velocity distribution within the reactor during stirring is shown in Table 1 under three liquid levels and corresponding positions of the second stirring paddle 23. The particle size distribution of the ternary cathode material precursor prepared in Example 1 is shown in Table 1. Figure 11As shown.

[0096] Comparative Example 1

[0097] The difference from Example 1 is that a reactor with a fixed and coaxial first and second fixed stirring paddle, as used in the prior art, is employed. The axial distance between the first fixed stirring paddle and the bottom of the reactor is 1 / 5 of the height of the reactor body 1, and the axial distance between the first and second fixed stirring paddles is 3 / 10 of the height of the reactor body 1. The preparation method includes:

[0098] Pretreatment steps: The temperature of the reactor is controlled at 50℃. Nitrogen gas is introduced into the reactor, followed by a 0.4~1.2 mol / L ammonia solution. Nitrogen gas serves as a protective gas, and the ammonia solution serves as the base solution for the reaction.

[0099] Feeding procedure: Start the first and second fixed agitators for stirring at a speed of 600 rpm. While stirring, introduce a 2.0 mol / L nickel-cobalt-manganese salt solution and a 1.2–3.6 mol / L ammonia solution into the reactor at a rate of 0.5 mL / min. Then, introduce 3.0 mol / L NaOH to control the pH of the solution in the reactor to 10.5 ± 0.01.

[0100] Aging, washing and drying steps: The solution in the reactor is aged for 10 hours, followed by washing and drying to obtain the ternary cathode material precursor.

[0101] Among them, Comparative Example 1 prepared a ternary cathode material precursor, such as Figure 4 and Figure 5 As shown in the diagram, during the preparation process, the distance between the second fixed stirring paddle and the bottom of the reactor is maintained at 1 / 2 of the height of reactor body 1 at three liquid levels. Figure 7 As shown, "H" represents the height of vessel 1. The reactor was analyzed using Fluent software. Figure 7 The flow field linear velocity distribution under the three liquid level states shown was simulated, and the simulation results are as follows: Figure 9 As shown. Figure 9 In this context, "Volume fraction of liquid" refers to the volume fraction of the liquid, and "initial state" refers to the initial state as shown in the image. Figure 7 The liquid volume fraction distribution in the reactor before stirring under three liquid levels and corresponding second fixed stirring shaft positions, where "final state" indicates the state before stirring. Figure 7 The liquid volume fraction distribution in the reactor during stirring is shown under three liquid levels and corresponding positions of the second fixed stirring shaft. "Linear velocity distribution" indicates the distribution under the following conditions: Figure 7The linear velocity distribution within the reactor during stirring is shown in Table 1 under three liquid levels and corresponding positions of the second fixed stirring shaft. The particle size distribution of the ternary cathode material precursor prepared in Comparative Example 1 is shown in Table 1. Figure 11 As shown.

[0102] It should be noted that, Figure 10 In this diagram, "Volume fraction of TM liquid" indicates the volume fraction of the liquid feed. "Fixed" indicates a fixed configuration, corresponding to the reactor in Comparative Example 1. "Mobile" indicates a movable configuration, corresponding to the reactor of this invention. "H" indicates the height of the reactor body. "Height of Z axis" indicates different heights along the axial direction (i.e., different positions along the height of the reactor body). Figures a and c are simulation results of the volume fraction distribution of the liquid feed in the reactor of Comparative Example 1 after 5 seconds of feeding, obtained using Fluent software. Figures b and d are simulation results of the volume fraction distribution of the liquid feed in the reactor of Example 1 after 5 seconds of feeding, obtained using Fluent software. Figure e is a schematic diagram of the volume fraction of the liquid feed at different positions along the axial direction in the reactor of this invention. Figure f is a comparison of the volume fraction of the liquid feed at different heights along the axial direction between Example 1 and Comparative Example 1.

[0103] Table 1:

[0104]

[0105] Depend on Figures 2-11 As shown in Table 1, the following can be seen:

[0106] from Figures 2-5 , Figure 11 As can be seen from the “SPAN” data column in Table 1, compared with Comparative Example 1, the ternary cathode material precursor obtained in Example 1 of the present invention has uniform particle size and good sphericity.

[0107] from Figures 6-9 It can be seen that the linear velocity distribution in the reactor used in Example 1 of this invention is relatively uniform under the three liquid level heights, and there is no obvious dead zone. However, in the reactor used in Comparative Example 1, the linear velocity in some areas is too high as the liquid level rises, which may cause the precursor to break. When the reactor is full of feed liquid, that is, when the liquid level reaches the top, there is an area with extremely low linear velocity in the upper part of the reactor used in Comparative Example 1, which is the stirring dead zone.

[0108] from Figure 10 It can be seen that after 5 seconds of feeding, the liquid in the reactor used in Example 1 of the present invention is evenly dispersed, while the liquid in the reactor used in Comparative Example 1 is still mainly in the upper part of the reactor. That is, the reactor of the present invention has a faster liquid dispersion efficiency during the feeding process.

[0109] While the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the invention to these descriptions. Various changes in form and detail can be made by those skilled in the art, including several simple deductions or substitutions, without departing from the spirit and scope of the invention.

Claims

1. A standby reactor for a ternary cathode material precursor system, characterized in that, include: The vessel body, The end cap is detachably connected to the vessel body; A stirring device, comprising: A stirring shaft extends axially, with one end fixedly connected to the end cap. The first stirring paddle is fixedly connected to the other end of the stirring shaft; The second stirring blade is sleeved on the outer periphery of the stirring shaft and is located between the first stirring blade and the end cap along the axial direction. A displacement component is used to drive the second stirring paddle to move along the axial direction.

2. The reaction vessel according to claim 1, characterized in that, The end cap is provided with an air inlet, the stirring shaft has a hollow structure, one end of the stirring shaft is connected to the air inlet, and the side wall of the stirring shaft is provided with an air outlet. External gas enters the hollow structure of the stirring shaft through the air inlet and flows out into the interior of the vessel through the air outlet.

3. The reaction vessel according to claim 2, characterized in that, The first stirring paddle includes a first stirring blade and a first elastic layer, and the second stirring paddle includes a second stirring blade and a second elastic layer. The first elastic layer covers the surface of the first stirring blade, and the second elastic layer covers the surface of the second stirring blade.

4. The reaction vessel according to claim 3, characterized in that, The first impeller is a turbine impeller, and the second impeller is a propeller impeller or a paddle impeller.

5. The reaction vessel according to claim 1, characterized in that, The displacement component includes: A drive motor is provided, and one end of the stirring shaft is fixedly connected to the end cover via the drive motor. A take-up pulley is located on the output shaft of the drive motor; A drive belt extends along the axial direction, one end of which is connected to the take-up pulley and the other end is connected to the second stirring paddle. The drive motor drives the output shaft of the drive motor to rotate, which in turn drives the take-up pulley to rotate to wind or unwind the transmission belt, thereby driving the second stirring paddle to move along the axial direction.

6. A method for preparing a ternary cathode material precursor, characterized in that, The preparation method is carried out using a reaction vessel as described in any one of claims 1-5, wherein the axial distance between the first stirring impeller and the bottom of the vessel body is 1 / 5 to 1 / 4 of the height of the vessel body, and the preparation method includes: Feeding steps: Start the first and second stirring paddles to stir. While stirring, introduce a nickel-cobalt-manganese salt solution with a metal ion concentration of 1.5~3.0 mol / L and a complexing agent with a concentration of 1.2~3.6 mol / L into the reactor at the same rate. Then, introduce a precipitant with a concentration of 1.5~3.0 mol / L to control the pH of the solution in the reactor to 10~12, thereby obtaining the ternary cathode material precursor. Specifically, when the liquid level in the reactor is lower than 1 / 10 to 1 / 8 of the height of the reactor body, the position of the second stirring paddle is controlled so that the axial distance between the second stirring paddle and the first stirring paddle is less than 1 / 5 to 1 / 4 of the height of the reactor body; when the liquid level in the reactor reaches 1 / 10 to 1 / 8 or more of the height of the reactor body, the position of the second stirring paddle is controlled so that the difference between the liquid level in the reactor and the axial height of the second stirring paddle is maintained at 1 / 10 to 1 / 4 of the height of the reactor body.

7. The preparation method according to claim 6, characterized in that, The moving speed of the second stirring paddle is 2 / 3 to 3 / 4 of the speed at which the liquid level rises in the reactor.

8. The preparation method according to claim 6, characterized in that, The stirring speed of both the first and second stirring paddles is 600~1000 rpm.

9. The preparation method according to claim 6, characterized in that, The end cap is provided with an air inlet, the stirring shaft has a hollow structure, one end of the stirring shaft is connected to the air inlet, and the side wall of the stirring shaft is provided with an air outlet. The process includes a pretreatment step before the feeding step, wherein the temperature of the reactor is controlled at 40~60℃, nitrogen gas is introduced into the hollow structure of the stirring shaft through the air inlet and flows out into the reactor body through the air outlet, and then a 0.4~1.2mol / L ammonia solution is introduced into the reactor.

10. The preparation method according to claim 6, characterized in that, The process includes aging, washing, and drying steps after the feeding step. The solution in the reactor is aged for 9-10 hours, followed by washing and drying to obtain the ternary cathode material precursor.

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