Fractional separation system, treatment method of positive electrode material and positive electrode material

Abstract

The invention discloses a grading separation system, a treatment method of a positive electrode material and the positive electrode material.The grading separation system comprises a first-stage grading smashing device and a second-stage grading separation device, and the second-stage grading separation device comprises a first air classifier, a second air classifier and a dust collector; the first air classifier is used for collecting the first dust collection material and separating the first dust collection material into a second dust collection material and a third dust collection material, and the second air classifier is used for collecting the third dust collection material and separating the third dust collection material into a fourth dust collection material and a fifth dust collection material. According to the grading and separating system, materials can be orderly circulated and screened layer by layer among a plurality of sequentially communicated air grading machines until an ideal grading state is realized, and the materials are refined and classified according to the required precision standard, so that the materials can be put into subsequent corresponding links such as chemical synthesis, material preparation, product processing and the like to be efficiently utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery recycling, and in particular to a grading separation system, a positive electrode material processing method and a positive electrode material. Background Art

[0002] In recent years, the rapid update and iteration of lithium battery technology has promoted the vigorous development of cathode material enterprises. The trend of raw material prices and fluctuations in government subsidies have also forced cathode material factories to actively seek new solutions for cost reduction and efficiency improvement. At present, manufacturers in the industry mainly reduce costs from two aspects: raw material cost reduction and process optimization. In the mass production process of cathode materials, fluidized bed airflow mills can be used to prepare ultra-hard, ultra-fine, and ultra-pure products. They are important equipment for crushing single crystal particles. In this process, dust collecting materials with too small particle size are produced. Generally, the output rate of cathode material dust collecting materials ranges from 0.5% to 2%. The dust collecting materials have small particle size and poor electrical properties, and the market price has dropped significantly compared to normal finished products. Therefore, the rationalization of the proportion of dust collecting materials has become one of the key control points of cathode material factories. If the proportion of dust collecting materials is too high, it is easy for normal particle size finished products to enter the dust collecting system; if the proportion of dust collecting materials is too low, it is easy for some ultra-fine particles to enter the product, resulting in a small particle size, which in turn affects important indicators such as specific surface, alkali content, and battery performance. Optimizing the proportion of dust collecting materials in positive electrode materials and rationally utilizing dust collecting materials is one of the important methods to achieve factory cost reduction and yield improvement.

[0003] There is no systematic classification management method in the existing methods for handling ultrafine particles of dust collection materials. The existing schemes do not have detailed data to support the practicality of differentiated treatment details for different dust collection material particle sizes, and cannot meet the needs of cost management. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a classification and separation system, which can classify materials according to the required accuracy standards, thereby achieving efficient utilization of materials.

[0005] The grading and separation system according to an embodiment of the present invention comprises: a first-stage grading and crushing device, comprising: a crushing device and a separator, wherein the crushing device is used to crush materials, the separator is connected to the crushing device, the separator is used to collect the crushed materials, and is used to separate the materials into qualified materials that meet the first condition and first dust-collecting materials that meet the second condition; a second-stage grading and separation device, comprising a first air classifier, a second air classifier and a dust collector, the feed inlet of the first air classifier is connected to the separator, the feed inlet of the second air classifier is connected to the fine powder discharge port of the first air classifier, and the The fine powder discharge port of the second air classifier is connected to the dust collector, the first air classifier is used to collect the first dust material, and to separate the first dust material into a second dust material that meets the third condition and a third dust material that meets the fourth condition, the second air classifier is used to collect the third dust material, and to separate the third dust material into a fourth dust material that meets the fifth condition and a fifth dust material that meets the sixth condition, wherein the particle size of the second dust material is larger than that of the third dust material, the particle size of the fourth dust material is larger than that of the fifth dust material, and the dust collector receives the fifth dust material.

[0006] According to the grading and separation system of the embodiment of the present invention, materials can be orderly circulated and screened layer by layer between a plurality of sequentially connected air classifiers until an ideal grading state is achieved, and the materials can be refined and classified according to the required accuracy standards so that they can be efficiently utilized in subsequent corresponding links such as chemical synthesis, material preparation, and product processing.

[0007] In some embodiments of the present invention, the classifying wheel of the first air classifier is a first classifying wheel, the classifying wheel of the second air classifier is a second classifying wheel, the rotation speed R1 of the first classifying wheel satisfies: 5897rpm≤R1≤6268rpm, the rotation speed R2 of the second classifying wheel satisfies: 7255rpm≤R1≤7584rpm; and / or, the classifying gap G1 of the first classifying wheel satisfies: 1.43μm≤G1≤1.52μm, the classifying gap G2 of the second classifying wheel satisfies: 1.18μm≤G1≤1.24μm, the motor of the first air classifier is a first motor, the motor of the second air classifier is a second motor, the first motor drives the first classifying wheel to rotate, the second motor drives the second classifying wheel to rotate, the motor frequency F1 of the first motor satisfies: 39.4HZ≤F1≤41.9HZ, the motor frequency F2 of the second motor satisfies: 48.5HZ≤F2≤5.7HZ.

[0008] In some embodiments of the present invention, the particle size D1 of the qualified material satisfies: 3.0μm≤D1≤4.0μm; the particle size D3 of the second dust collecting material satisfies: 1.5μm≤D3<3.0μm; the particle size D5 of the fourth dust collecting material satisfies: 0.9μm≤D5<1.5μm; the particle size D6 of the fifth dust collecting material satisfies: D6<0.9μm.

[0009] In some embodiments of the present invention, the crushing device includes: any one of: a jet mill, a mechanical mill, and a colloid mill.

[0010] In some embodiments of the present invention, the bottom of the cyclone separator has a first material distribution port for conveying the qualified material, and the top of the cyclone separator has a second material distribution port for conveying the first dust-collecting material.

[0011] In some embodiments of the present invention, the first air classifier and the second air classifier are both vertical turbine classifiers, the top of the vertical turbine classifier is provided with a feed inlet, the bottom of the vertical turbine classifier is provided with a coarse powder discharge port, and the side of the vertical turbine classifier is provided with a fine powder discharge port;

[0012] In some embodiments of the present invention, the dust collector comprises: a sintered plate.

[0013] The invention also provides a method for processing the positive electrode material.

[0014] According to the processing method of the positive electrode material of the embodiment of the present invention, it is used to process the second dust material, the fourth dust material and the fifth dust material separated by the grading separation system. The processing method of the positive electrode material includes: directly mixing the second dust material with the finished product of qualified material to obtain a first mixed material; back-mixing the fourth dust material at the mixing point and then sintering to achieve the regrowth of single crystal particles to obtain a second mixed material; downgrading the fifth dust material.

[0015] In some embodiments of the present invention, the direct blending of the second dust collecting material with the finished product of qualified material includes: the blending ratio of the second dust collecting material is 30%-50% based on the weight of the first mixed material; preferably, the blending frequency of the spiral belt is 40Hz-50Hz, and the blending time is 3h. In this application, the finished product of qualified material refers to the product obtained by post-processing the qualified material, and the post-processing process can be to screen and remove iron from the qualified material to obtain the finished product of qualified material; or to screen and remove iron from the qualified material and then mix and sinter with the coating additive to obtain the coated product, and then screen and remove iron from the coated product to obtain the finished product of qualified material.

[0016] In some embodiments of the present invention, sintering after re-blending the fourth dust collection material at the compounding stage to achieve the regrowth of single crystal particles includes: mixing the fourth dust collection material with the materials of the production line at the compounding process to obtain a mixed material, where the materials of the production line at least include: a precursor of the cathode material, a lithium source, and a doping element M, and the compounding ratio of the doping element M is greater than or equal to 0. Based on the weight of the second mixed material, the compounding ratio of the fourth dust collection material is 1 wt% - 5 wt%; sintering the obtained mixed material under a process atmosphere; successively performing coarse crushing, fine crushing, and sieving on the sintered material to obtain the second mixed material containing the re-blended treatment of the cathode material crushing dust collection material.

[0017] In some embodiments of the present invention, the temperature of the sintering is 800°C - 1000°C, and the time is 20 h - 30 h; and / or, the oxygen content of the process atmosphere is ≥ 90 vol%, and the gas flow rate is 600 - 1300 Nm 3 / h; and / or, the compounding ratio of the fourth dust collection material is 4.1 wt% - 5 wt%.

[0018] The present invention also provides a cathode material, which includes a compound LiNi shown by the following molecular formula x Co y Mn z M a O2, where 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 ≤ a < 0.5. The cathode material includes: 50 wt% - 70 wt% of finished products prepared by post-treatment of qualified materials separated by a classification separation system, and 30 wt% - 50 wt% of the first mixed material obtained by the treatment method of the cathode material; or, the cathode material includes: at least 95 wt% of finished products prepared by post-treatment of qualified materials separated by a classification separation system, or further includes 1 wt% - 5 wt% of the second mixed material obtained by the treatment method of the cathode material. In this application, the post-treatment includes sieving and iron removal of the qualified materials to obtain finished products; or sieving and iron removal of the qualified materials, then mixing with a coating additive, sintering, and then performing sieving and iron removal again to obtain coated material finished products.

[0019] In some embodiments of the present invention, in terms of the molar percentage of transition metals, the materials crushed and separated by the classification separation system are single crystal multi-component cathode materials with a Ni content of greater than or equal to 60%.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0022] Figure 1 Schematic diagram of the structure of an air classifier according to some embodiments of the present invention.

[0023] Figure 2 It is a structural schematic diagram of a grading and separation system according to some embodiments of the present invention (the wireframes marked with numbers 1000 and 2000 in the figure are only for the convenience of distinguishing the first-stage grading and crushing device and the second-stage grading and separation device. The first-stage grading and crushing device and the second-stage grading and separation device are framed in the wireframe, and the wireframe is not a physical structure).

[0024] Figure 3 Schematic diagram of the structure of a rotating cage according to some embodiments of the present invention.

[0025] Figure 4 is a cross-sectional view of a rotating cage according to some embodiments of the present invention.

[0026] Figure 5 is a perspective view of a rotating cage (with a disturbance rod) according to some embodiments of the present invention.

[0027] Figure 6 Schematic diagram of a process of a grading separation system and a method for processing a positive electrode material according to some embodiments of the present invention.

[0028] Figure 7 3 is a scanning electron microscope comparison diagram of the dust collecting material X according to some embodiments of the present invention and the ultrafine particles A, ultrafine particles B, and ultrafine particles C produced by classification.

[0029] Figure 8 3 is a scanning electron microscope comparison diagram of the dust collecting material Y and the ultrafine particles A, ultrafine particles B, and ultrafine particles C produced by classification according to some embodiments of the present invention.

[0030] Fig. 9 This is a comparison of the high temperature cycle data of the mixed back-blending product obtained in step 3 of the first embodiment and the normal material.

[0031] Fig.10 This is a comparison of the high temperature cycle data of the mixed back-blending product obtained in step 3 of the second embodiment and normal materials.

[0032] Fig.11 This is a comparison table of the finished product indicators of the single crystal positive electrode material X in the first embodiment and the back-doped material X-HC in step 3.

[0033] Fig.12 This is a comparison table of the finished product indicators of the single crystal positive electrode material X in the second embodiment and the back-doped material Y-HC in step 3.

[0034] Reference numerals:

[0035] 100. Air classifier;

[0036] 1. Casing; 11. Volute; 12. Conical funnel; 13. First discharge port; 14. Second discharge port; 15. First air inlet;

[0037] 2. Classifying wheel; 21. Rotating cage; 20. Blade; 211. First blade; 212. Second blade; 22. First annular plate; 23. Second annular plate; 24. Disturbance rod;

[0038] 10000, classification and separation system;

[0039] 1000, first-stage classification and crushing device; 200, crushing device; 300, separator;

[0040] 2000. Second stage classification and separation device; 400. Dust collector. DETAILED DESCRIPTION

[0041] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0042] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0043] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In recent years, the rapid update and iteration of lithium battery technology has promoted the vigorous development of positive electrode material companies. The trend of raw material prices and fluctuations in government subsidies have also forced positive electrode material factories to actively seek new solutions to reduce costs and increase efficiency. At present, manufacturers in the industry reduce costs mainly from two aspects: reducing the cost of raw materials and optimizing processes. In the mass production process of positive electrode materials, fluidized bed airflow mills can be used to prepare ultra-hard, ultra-fine, and ultra-pure products. They are important equipment for crushing single crystal particles. The dust collected in this process, in the related technology, due to the insufficient separation accuracy of the cyclone separator in the crushing device, the dust collected accounts for a higher proportion than the qualified material. Some qualified materials will also enter the airflow and be collected together as dust collected. The existing dust collection process is relatively rough, usually downgraded, which will undoubtedly increase production costs. How to optimize the separation equipment and further perform efficient treatment of the dust collected by graded separation is the purpose of this invention.

[0046] Based on this, the present application first proposes an air classifier 100, which can be used in conjunction with a cyclone separator in a crushing device. The air classifier has a simple structure, and the air classifier 100 provided by the present application has good separation accuracy and separation efficiency.

[0047] Reference below Figure 1-Figure 5 An air classifier 100 according to an embodiment of the present invention is described.

[0048] Please refer to Figure 1 and Figure 2 In some embodiments of the present invention, an air classifier 100 includes: a casing 1 and a classifying wheel 2, the casing 1 has a feed port 16 at the top, a first discharge port 13 at the bottom, a second discharge port 14 at the side of the casing 1, the classifying wheel 2 is arranged in the casing 1, the classifying wheel 2 includes a rotating cage 21, and the blades 20 of the rotating cage 21 include a first blade 211 and a second blade 212, the width of the first blade 211 is greater than the width of the second blade 212, and in the circumferential direction of the rotating cage 21, a plurality of first blades 211 and a plurality of second blades 212 are arranged alternately.

[0049] In terms of particle separation, blades 20 of different widths can effectively handle particles of different sizes. The wide first blade 211 can have a strong blocking and separation effect on particles of larger sizes. When the particle-containing airflow enters the cage 21 of the grading wheel 2, when the particles of larger sizes hit the first blade 211, the wider blade can provide a larger collision area, making it easier to be intercepted, thereby guiding these large particles to move to the bottom of the casing 1 under the action of centrifugal force and be discharged from the first discharge port 13. The narrow second blade 212 is conducive to processing particles of smaller sizes. Smaller particles can bypass the second blade 212 with the airflow, so that the small particles continue to move in the cage 21 under the carry of the airflow, so that the preliminary separation of large and small particles can be achieved, so that particles of smaller sizes have the opportunity to be discharged from the second discharge port 14 on the side.

[0050] From the perspective of the impact on the airflow, this staggered blade structure can make the airflow more uniform and stable. The wide blades and narrow blades appear alternately, which will not cause the airflow to be excessively blocked or change drastically in a certain part. During the rotation of the rotating cage 21, the wide blades can cause the airflow to form a strong disturbance locally, which is conducive to the separation of large particles, while the narrow blades have relatively small disturbances on the airflow, so that the airflow can quickly return to a relatively stable state after passing through the narrow blade area, which helps small particles to be further screened in the stable airflow, thereby improving the accuracy and efficiency of classification.

[0051] The air classifier 100 according to the embodiment of the present invention has a simple structure and can reduce the production cost of the equipment. The staggered blade structure can make the airflow more uniform and stable, which helps small particles to be further screened in the stable airflow, thereby improving the accuracy and efficiency of classification.

[0052] In some embodiments of the present invention, in the radial direction of the rotating cage 21 , a distance H1 between an outer edge of the second blade 212 and an outer edge of the rotating cage 21 satisfies: 3 mm ≤ H1 ≤ 7 mm.

[0053] Exemplarily, H1 may be: 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm.

[0054] That is to say, the structure of the blades 20 of the cage 21 can determine the flow field inside the air classifier 100. Therefore, under the condition of ensuring the most suitable operating parameters of the classification equipment, by reasonably improving the structural parameters of the blades 20 of the cage 21, the effect of improving the classification performance can be achieved. In the present application, when the distance is less than 3mm, the standard deviations of the radial and tangential velocities are larger than those at other distances, because when the air volume is constant, the velocity distribution at the outer edge of the cage 21 is mainly affected by the resistance of the airflow through the blades 20 and the inertial anti-vortex strength between the blades 20. If the surface area of ​​the blades 20 is too small, the spatial volume of the blade 20 channel increases, the inertial vortex strength of the airflow between the blades 20 will increase, and the velocity fluctuation will be large. When the distance is greater than 7mm, backflow is likely to occur at the airflow outlet between the blades 20. It is easy to weaken the stability of the flow field; therefore, when the distance between the short blade and the outer edge of the cage 21 is 3mm-7mm, preferably 4mm, the airflow velocity distribution on the circumference of the outer edge of the cage 21 is uniform, and the flow field between the blades 20 is stable.

[0055] In some embodiments of the present invention, reference Figure 1 and Figure 2 The casing 1 includes a volute 11 and a conical funnel 12 connected to the lower end of the volute 11. The grading wheel 2 is located in the volute 11, and the first discharge port 13 is located at the bottom of the conical funnel 12. In other words, the volute 11 provides an adaptation space for the operation of the grading wheel 2, regulates the direction of the airflow, and helps to accurately sort the materials according to the particle size. The conical funnel 12 is cleverly connected, and with its narrow bottom and wide top structure, it effectively gathers the separated coarse particles, allowing them to flow smoothly to the first discharge port 13 at the bottom to avoid accumulation of residues. The overall structure is compact and reasonable, which not only ensures a smooth and efficient separation process, but also facilitates the stable operation of the equipment and reduces maintenance costs.

[0056] In some embodiments of the present invention, reference Figure 2 The rotation axis of the rotating cage 21 extends in the horizontal direction, and the second discharge port 14 is located on the rotation axis.

[0057] Reference Figure 2 In the example shown, the dust material falls from the radial side of the cage 21, that is, the upper side, to the area of ​​the cage 21. Under the suction of the centrifugal fan, the particles are affected by the centripetal drag of the airflow entering the cage 21, the centrifugal force generated by the circular motion of the airflow in the annular area, and the gravity on themselves. The coarse particles can fall well to the conical funnel 12 below. Since the rotation axis of the cage 21 extends in the horizontal direction, the second discharge port 14 is located on the rotation axis. The fine particles can be discharged in a shorter path and in a smoother manner under the entrainment of the airflow, which can better reduce the risks of interference such as wall collision and turbulence, can better improve the separation efficiency of the dust material, and enhance the stability and accuracy of the equipment operation.

[0058] In some embodiments of the present invention, in the axial direction, the length L1 of the first blade 211 and the length L2 of the second blade 212 satisfy: 0.78≤L2 / L1≤0.85.

[0059] That is to say, the shorter second blade 212 cooperates with the relatively longer first blade 211. When guiding the airflow, the longer first blade 211 can more fully comb and regularize the direction of the airflow, and the shorter second blade 212 can fine-tune the airflow velocity and direction, which is beneficial to improving the screening effect of the dust collection material. The shorter second blade 212 cooperates with the relatively longer first blade 211 to reduce sudden changes in the airflow, enhance classification stability, and improve overall separation accuracy and efficiency.

[0060] In some embodiments of the present invention, the rotating cage 21 also includes a first annular plate 22 and a second annular plate 23, the first blade 211 is connected between the first annular plate 22 and the second annular plate 23, the second blade 212 includes a relative free end and a fixed end, and the fixed ends of the second blade 212 on both sides of the first blade 211 are respectively installed on the first annular plate 22 and the second annular plate 23.

[0061] Combination Figure 3 As shown, the second blade 212 connected to the first annular plate 22 is called an upper blade, and the second blade 212 connected to the second annular plate 23 is called a lower blade. A plurality of upper blades and a plurality of lower blades are staggered around the axis of the rotating cage 21. Therefore, from the perspective of the impact on the airflow, when the airflow carries the particles into the rotating cage 21, the staggered upper blades and lower blades can guide part of the airflow to change its direction, slow down the local flow rate, and cause large-size particles to settle due to inertia; and can further disrupt the originally disordered rhythm of the airflow, so that it forms multiple "tributaries" with orderly strengths and directions, avoiding the airflow carrying all the particles "rushing past", and ensuring that small-size particles can continue their sorting journey in a relatively stable and controllable airflow environment.

[0062] In terms of particle classification efficiency, the upper and lower blades are arranged at intervals to create a clearly layered classification "channel" for particles of different sizes. Large particles are blocked and diverted by the blades, and are discharged to the bottom of the casing with the help of centrifugal force; small particles are accurately separated from the second discharge port on the side with the help of the special airflow environment created by the blades, which can greatly reduce the mixing and misjudgment of coarse and fine particles, and significantly improve classification accuracy and overall efficiency.

[0063] In some embodiments of the present invention, reference Figure 4 and Figure 5 , the number N of the plurality of first blades 211 and the number N of the plurality of second blades 212 satisfies: 30≤N≤35.

[0064] Exemplarily, the number and N can be 30, 31, 32, 33, 34, 35.

[0065] In the above example, when the equipment is running, enough blades 20 that meet the above conditions can finely "cut" and comb the airflow to form a uniform, stable and orderly flow field, avoid local turbulence or disorder in the airflow, and improve the effect of separating coarse and fine particles along a predetermined trajectory.

[0066] In some embodiments of the present invention, reference Figure 5 The outer edge of the blade 20 of the rotating cage 21 is provided with a disturbance rod 24, which extends in the radial direction of the rotating cage 21. That is to say, the disturbance rod 24 extending in the radial direction continuously cuts and disturbs the airflow around the rotating cage as the rotating cage 21 rotates, just like inserting a fast stirring blade in a steady water flow, which greatly enhances the turbulence intensity around the rotating cage. The high-intensity turbulence forces the material particles to break free from the original relatively stable state, and the materials that may have originally agglomerated or unevenly layered are fully broken up, significantly increasing the dispersion around the rotating cage, and the coarse and fine particles can be separated more thoroughly.

[0067] Exemplarily, the crushing device 200 may be a jet mill, a mechanical mill or a colloid mill.

[0068] Exemplarily, the separator 300 may be a cyclone separator.

[0069] Exemplarily, a plurality of disturbance rods 24 may be provided, and the plurality of disturbance rods 24 are spaced apart from each other along the circumference of the rotating cage 21 .

[0070] In some embodiments of the present invention, reference Figure 2 A first air inlet 15 is also provided on the side of the housing 1, and in the up-down direction, the first air inlet 15 is located between the classifying wheel 2 and the first discharge port 13. That is, in the process of the coarse powder particles falling downward toward the first discharge port 13, the airflow entering from the first air inlet 15 can centrally wash the coarse powder particles to further remove the remaining ultrafine particles, thereby facilitating further improving the classification effect of the coarse powder particles.

[0071] In some embodiments of the present invention, reference Figure 2 In the horizontal direction, the grading wheel 2 and the second discharge port 14 are arranged opposite to each other. Therefore, after the material is screened by the airflow, the fine particles move directly toward the second discharge port 14 under the entrainment of the airflow. The horizontal relative design shortens the conveying path of the fine particles and reduces the risk of material deposition or secondary mixing caused by factors such as airflow turbulence and wall collision. In this way, it can not only ensure the separation accuracy and allow the fine particles to be discharged efficiently and accurately, but also help maintain the stable operation of the equipment and continuously output high-quality separation effects.

[0072] In some embodiments of the present invention, reference Figure 5, the blades 20 of the cage 21 are arc-shaped blades, and the axis of the arc-shaped blades is parallel to the rotation axis of the cage 21. In other words, the blades 20 of the cage 21 are arc-shaped blades, which can help improve the stability of the airflow field. The arc-shaped design fits the direction of the airflow, and can eliminate the turbulent "dead corners" caused by right angles and corners, allowing the airflow to smoothly shuttle between the blades 20, which is conducive to improving the separation effect of the dust collection material. In addition, compared with the outlet backflow easily caused by the traditional rectangular blades 20, the arc-shaped blades can guide the airflow to be discharged more smoothly, reduce the interference of countercurrent, make the dust collection material more evenly and accurately stressed, and improve the separation accuracy and separation efficiency of the dust collection material.

[0073] In some embodiments of the present invention, reference Figure 4 and Figure 5 The blades 20 of the rotating cage 21 include a first blade 211 and a second blade 212 . The length of the first blade 211 is greater than that of the second blade 212 . In the circumferential direction of the rotating cage 21 , a plurality of first blades 211 and a plurality of second blades 212 are alternately arranged.

[0074] That is to say, the installation form of the blades 20 of the cage 21 is the staggered installation of long blades and short blades. Improving the cage 21 with equal-length blades to the cage 21 with staggered installation of long blades and short blades can effectively improve the distribution of tangential and radial velocities on the outer cylindrical surface of the cage 21, and is conducive to improving classification accuracy and reducing classification particle size. Compared with equal-length blades, the radial velocity of the airflow at the inlet of the cage 21 is reduced and the tangential velocity is increased by adopting the staggered blade 20 form. This is due to the increase in the cross-sectional area at the airflow inlet of the improved cage 21 under the same air volume and rotation speed. Under the same conditions, the tangential and radial velocity distribution of the airflow in the vortex air classifier 100 of the cage 21 with staggered blades 20 is uniform, and the velocity fluctuation is small, so fine powder particles with a narrow particle size distribution range can be obtained better.

[0075] The present invention also provides a classification and separation system 10000 having the air classifier 100 of the above embodiment.

[0076] Reference Figure 2According to an embodiment of the present invention, a grading and separation system 10000 includes a first-level grading and crushing device 1000 and a second-level grading and separation device 2000. The first-level grading and crushing device 1000 includes a crushing device 200 and a separator 300. The crushing device 200 is used to crush materials. The separator 300 is connected to the crushing device 200. The separator 300 is used to collect materials after being crushed by the materials, and is used to separate the materials into qualified materials that meet the first condition and first dust collecting materials that meet the second condition. The qualified materials are transported from the first material distribution port, and the first dust collecting materials that meet the second condition are transported toward the second material distribution port, wherein the particle size of the qualified materials is larger than that of the first dust collecting materials. The second-level grading and separation device 2000 includes: at least one air classifier 100, wherein, when there are multiple air classifiers 100, the feed port of one of two adjacent air classifiers 100 is connected to the second material distribution port, and the second discharge port 14 is connected to the feed port of another air classifier 100.

[0077] Exemplarily, the material first enters the crushing device 200 of the first-stage classification and crushing device 1000, where the material is crushed. As the crushing operation continues, fine powder that meets the particle size requirements enters the separator 300, and coarse powder that does not meet the particle size requirements continues to enter the crushing device 200 for crushing. The separator 300 performs a separation operation on the fine powder according to the pre-set conditions to obtain qualified materials discharged from its bottom (i.e., the first material distribution port) and dust collection materials discharged from its exhaust port (i.e., the second material distribution port). Specifically, qualified materials with relatively large particle sizes that meet the first condition are accurately transported out from the first material distribution port under the action of the separator 300 and enter the corresponding subsequent processing flow or temporary storage area; while the first dust collection materials with smaller particle sizes that meet the second condition are directed to the second material distribution port to start the next step of fine classification.

[0078] The first dust collecting material outputted from the second material distribution port of the first-stage classification and crushing device 1000 is then transported to the second-stage classification and separation device 2000. If the second-stage classification and separation device 2000 is only equipped with one air classifier 100, the second dust collecting material directly enters the feed port of the air classifier 100. Inside the air classifier 100, with the help of key working mechanisms such as high-speed rotating airflow, the second dust collecting material is finely classified and screened again according to the physical properties of the material such as particle size and density, so that materials of different specifications and levels are effectively separated and each is outputted from the corresponding discharge port, so as to achieve a more accurate classification effect and meet the diversified production and processing needs.

[0079] If the second-stage classification and separation device 2000 includes multiple air classifiers 100, at this time, the second dust collection material first enters the feed port of the first air classifier 100 connected thereto, and after the initial fine screening here, a part of the material is output from the discharge port of the air classifier 100, and the other part of the material is transported to the feed port of the next adjacent air classifier 100, and the above-mentioned fine classification process is repeated. In this way, the material is orderly circulated and screened layer by layer between multiple sequentially connected air classifiers 100 until the ideal classification state is achieved, and the material is refined and classified according to the required accuracy standard, so that it can be put into the subsequent corresponding links such as chemical synthesis, material preparation, product processing, etc. for efficient use.

[0080] According to the grading and separation system 10000 of the embodiment of the present invention, materials can be orderly circulated and screened layer by layer between a plurality of sequentially connected air classifiers 100 until an ideal grading state is achieved, and the materials can be refined and classified according to the required accuracy standards so that they can be efficiently utilized in subsequent corresponding links such as chemical synthesis, material preparation, and product processing.

[0081] Continue to refer to Figure 2 According to some embodiments of the present invention, a grading and separation system 10000 includes: a first-stage grading and crushing device 1000 and a second-stage grading and separation device 2000, wherein the first-stage grading and crushing device 1000 includes: a crushing device 200 and a separator 300, wherein the crushing device 200 is used to crush materials, the separator 300 is connected to the crushing device 200, and the separator 300 is used to collect the crushed materials and to separate the materials into qualified materials that meet the first condition and first dust-collecting materials that meet the second condition, wherein the particle size of the qualified materials is larger than that of the first dust-collecting materials; the second-stage grading and separation device 2000 includes a first air classifier, a second air classifier and a dust collector 400, wherein the first air classifier The feed port of the second air classifier is connected to the separator 300, the feed port of the second air classifier is connected to the fine powder discharge port of the first air classifier, the fine powder discharge port of the second air classifier is connected to the dust collector 400, the first air classifier is used to collect the first dust material, and is used to separate the first dust material into the second dust material that meets the third condition and the third dust material that meets the fourth condition, the second air classifier is used to collect the third dust material, and is used to separate the third dust material into the fourth dust material that meets the fifth condition and the fifth dust material that meets the sixth condition, wherein the particle size of the second dust material is larger than the particle size of the third dust material, the particle size of the fourth dust material is larger than the particle size of the fifth dust material, and the dust collector 400 receives the fifth dust material.

[0082] That is, the material enters the first-stage classification crushing device 1000 and is crushed in the crushing device 200. The crushed material produces dust material, which enters the separator 300 connected thereto. The separator 300 plays a role of preliminary screening, and divides the dust material into qualified material (larger particle size) and first dust material (smaller particle size) according to the particle size. This completes the first-stage classification. Then, the second-stage classification separation device 2000 starts working. The first dust material is sent to the first air classifier, where it is separated into the second dust material (relatively larger particle size) and the third dust material (relatively smaller particle size). Then, the third dust material enters the second air classifier, and is further separated into the fourth dust material (relatively larger particle size) and the fifth dust material (relatively smaller particle size), and finally the fifth dust material is collected by the dust collector 400.

[0083] Exemplarily, the qualified material that meets the first condition is a product of normal particle size and can be directly used in the preparation of single crystal positive electrode materials. The particle size of the second dust collection material is relatively large, and it can be directly mixed with the finished product of the qualified material at the finished product spiral belt to obtain a first mixture, which can then be used for the preparation of single crystal positive electrode materials. The particle size of the fourth dust collection material that meets the fifth condition is relatively medium, and it can be back-mixed and sintered at the mixing point to achieve single crystal particle regrowth to obtain a second mixture, which can be used for the preparation of single crystal positive electrode materials. The particle size of the dust collection material that meets the sixth condition is relatively small, and it can be directly downgraded or used as waste.

[0084] According to the grading and separation system 10000 of the embodiment of the present invention, materials can be orderly circulated and screened layer by layer between a plurality of sequentially connected air classifiers 100 until an ideal grading state is achieved, and the materials can be refined and classified according to the required accuracy standards so that they can be efficiently utilized in subsequent corresponding links such as chemical synthesis, material preparation, and product processing.

[0085] In the above example, regarding the finished spiral ribbon, in the process of preparing the positive electrode material, after mixing and grinding, the material may need to be transported and initially agglomerated through the finished spiral ribbon. For example, after mixing a variety of positive electrode material raw materials (such as lithium source, iron source, manganese source, etc.) and grinding them to a suitable particle size, the finished spiral ribbon can transport these materials to the next synthesis reaction process. At the same time, during the transportation process, the stirring action of the spiral ribbon may cause some fine particles to a certain extent agglomerate, which is conducive to the fusion of particles and the uniformity of the reaction in the subsequent reaction process.

[0086] Exemplarily, the first to sixth conditions mentioned above can be divided into qualified materials and first to fifth dust collecting materials according to the particle size of the dust collecting materials.

[0087] In some embodiments of the present invention, the classifying wheel 2 of the first air classifier is a first classifying wheel, and the classifying wheel 2 of the second air classifier is a second classifying wheel.

[0088] Exemplarily, the rotation speed R1 of the first classifying wheel satisfies: 5897rpm≤R1≤6268rpm, and the rotation speed R2 of the second classifying wheel satisfies: 7255rpm≤R1≤7584rpm;

[0089] In the present invention, the first classifying wheel or the second classifying wheel can be driven by a V-belt with a fixed transmission ratio, and the rotation speed of the first classifying wheel or the second classifying wheel can be controlled by a frequency converter. When the rotation speed of the first classifying wheel meets the range, a fine powder product (i.e., the third dust collection material) with a mass fraction of 97% of particles with a particle size of less than 1.5 μm can be separated, and when the rotation speed of the second classifying wheel meets the range, a fine powder product (i.e., the fifth dust collection material) with a mass fraction of 97% of particles with a particle size of less than 0.9 μm can be separated.

[0090] Exemplarily, the classification gap G1 of the first classification wheel satisfies: 1.43 μm ≤ G1 ≤ 1.52 μm, and the classification gap G2 of the second classification wheel satisfies: 1.18 μm ≤ G1 ≤ 1.24 μm,

[0091] The classification gap of the classifying wheel 2 refers to the distance between the blades of the classifying wheel 2. This gap is a key parameter, which has an important influence on the classification accuracy and classification efficiency of the particles.

[0092] When the crushed material enters the area where the classifying wheel 2 is located, the classifying wheel 2 rotates at high speed. During the rotation process, the material particles are subjected to the centrifugal force. Larger particles are subjected to relatively strong centrifugal force due to their large mass, and will be thrown to the edge of the classifying wheel 2; while smaller particles are subjected to relatively small centrifugal force, and can pass through the gap of the classifying wheel 2 under the entrainment of the airflow, thereby achieving the separation of large and small particles. The size of the classification gap directly determines the range of particle sizes that can pass. If the gap is too large, some larger particles that should have been thrown out by the classifying wheel 2 may be mixed into the fine particles passing through because the gap is too wide, resulting in a decrease in classification accuracy; on the contrary, if the gap is too small, although the classification accuracy can be improved, it may cause difficulty in the passage of fine particles and reduce the classification efficiency. Therefore, the classification gap that meets the above conditions can enable the first air classifier with the first classifying wheel to better classify the first dust collection material into the second dust collection material and the third dust collection material, and the second air classifier with the second classifying wheel to better classify the third dust collection material into the fourth dust collection material and the fifth dust collection material.

[0093] In addition, different positive electrode materials have different characteristics such as particle shape, hardness and density. For example, for positive electrode materials with higher density, at the same rotation speed, the centrifugal force on the particles is greater. Therefore, when processing such materials, it may be necessary to adjust the grading gap appropriately to ensure accurate grading. If the material particles are irregular in shape, it will also affect their motion trajectory in the grading wheel 2, and then affect the setting of the grading gap. Therefore, the grading gap that meets the above conditions can better improve the grading accuracy of the first air classifier and the second air classifier.

[0094] Exemplarily, the motor of the first air classifier is the first motor, and the motor of the second air classifier is the second motor. The first motor drives the first classifying wheel to rotate, and the second motor drives the second classifying wheel to rotate. The motor frequency F1 of the first motor satisfies: 39.4HZ≤F1≤41.9HZ, and the motor frequency F2 of the second motor satisfies: 48.5HZ≤F2≤5.7HZ.

[0095] The air classifier 100 is a device that separates particles of different sizes through an air flow field. When the motor frequency of the classifying wheel 2 and the classifying gap of the classifying wheel 2 meet the above conditions, the second-stage classification and separation device 2000 can separate suitable products with different large, medium and small particle size distributions. The product with a small particle size distribution (i.e., the fifth dust collection material) can be directly classified as waste treatment or downgrading treatment, the product with a medium particle size distribution (i.e., the fourth dust collection material) can be used as an intermediate product of the positive electrode material, added in the mixing stage, and formed into a conventional product after sintering; the product with a large particle size distribution (i.e., the second dust collection material) can be used as the final product and mixed with conventional products in proportion.

[0096] Exemplarily, the first air classifier and the second air classifier are both dynamic air classifiers, which include a classifying chamber and a classifying wheel 2, air guide blades and a material dispersion mechanism arranged in the classifying chamber from top to bottom, wherein the classifying wheel 2 is horizontally installed at the top of the classifying chamber, and a top feeding method is adopted, and the material enters the classifier under the action of gravity.

[0097] The air classifier 100 is mainly divided into a static air classifier and a dynamic air classifier according to whether it has a driving component. The static air classifier has a relatively simple structure and is easy to maintain, but the classification accuracy is not high and there are fewer means to adjust the particle size. A cyclone separator is a typical static classifier; a dynamic air classifier is a vortex air classifier, which is mainly composed of a volute, a conical funnel, air guide blades, a rotating cage, a spreading plate, etc. The air sucked by the centrifugal fan enters the volute from the air inlet, and enters the annular space formed by the inner edge of the air guide blade and the outer edge of the rotating cage after the guiding effect of the air guide blade. The material to be classified falls from the feed port at the top of the volute to the spreading plate on the rotating cage. The material is dispersed as the spreading plate rotates, and loses momentum after being hit by the buffer plate, falls into the annular space, and is evenly mixed with the airflow guided by the air guide blade. In the annular zone, the material particles are acted upon by the centrifugal fan, the centripetal force of the airflow entering the cage, the centrifugal force generated by the circular motion of the airflow in the annular zone, and the gravity they are subjected to. Due to the different masses of coarse and fine particles, the magnitude of the forces they are subjected to is different. Under the action of the above three forces, the separation of coarse and fine particles is achieved. The fine powder particles enter the cage with the airflow, and then go out from the fine powder outlet of the vortex air classifier. Finally, the cyclone dust collector and bag dust collector separate the fine powder particles from the airflow, thereby obtaining the final fine powder product. The coarse powder particles fall from the annular zone into the conical funnel. Compared with the centrifugal static classifier, its classification accuracy and classification efficiency are greatly improved, and there are more adjustable operating parameters, which is more suitable for precision classification.

[0098] In the present invention, since the material is fed from directly above the classifier, the classifying wheel 2 is directly below the feed port, which can optimize the distribution and dispersion of the product.

[0099] For example, the first air classifier and the second air classifier are both vertical turbine classifiers. Therefore, in terms of classification efficiency, the first air classifier and the second air classifier can ensure that the feeding point is classified within a range of more than 90% of the circumference of the rotating cage 21 regardless of the feeding method adopted. In terms of classification accuracy, the vertical classifier can be filled with air from all sides, the flow field is relatively stable, and the particle size of the classified products is uniform.

[0100] In some embodiments of the present invention, the particle size D1 of the qualified material satisfies: 3.0μm≤D1≤4.0μm; the particle size D3 of the second dust collecting material satisfies: 1.5μm≤D3<3.0μm; the particle size D5 of the fourth dust collecting material satisfies: 0.9μm≤D5<1.5μm; the particle size D6 of the fifth dust collecting material satisfies: D6<0.9μm.

[0101] That is to say, the first air classifier discharges ultrafine particles with a size of D50>1.5μm (i.e., the second dust collection material) from the lower discharge port, and fine powder with a particle size of D50<1.5μm (i.e., the third dust collection material) is output to the feed valve of the second air classifier through the outlet; the second air classifier discharges ultrafine particles with a size of D50=0.9μm-1.5μm (i.e., the fourth dust collection material), and ultrafine particles with a size of D5<0.9μm (i.e., the fifth dust collection material) are collected by the dust collector 400, which can be a sintered plate. The equipment technical transformation method and material flow method of the grading and separation system 10000 of the present invention are as follows: Figure 2 When the dust collected is classified according to the above-mentioned particle size range, each material obtained not only has a narrower particle size distribution than the single dust collected by the traditional air jet mill, but also can reduce the waste ratio of the dust collected by about 85%, that is, 85% of the dust collected can be recycled.

[0102] Preferably, the D50 of the ultrafine particles produced by the first air classifier is 0.3 μm, and the D100 is 2 μm. The entire separation process is a non-splashing particle and low-wear operation mode. After the material enters the first air classifier, the classification air flows through the classification wheel 2 in the centripetal direction. In this process, the classification wheel 2 extracts ultrafine particles from the feed and transports them to the ultrafine particle discharge port. The coarse material rejected by the classification wheel 2 tilts downward. Before the coarse material leaves the classifier, it is again centrally flushed by air to remove the remaining ultrafine particles. This will achieve a very clean coarse particle fraction. In the classification process of the eddy current air classifier, process parameters such as the rotation speed of the classification wheel 2, the inlet wind speed and the feed speed are the main factors affecting the classification accuracy and classification performance. The process parameters can be adjusted to meet the classifier's requirements for the classification of specific materials and to optimize the internal flow field of the classifier. The operation process, output efficiency, classification accuracy, and machine cost of the equipment are all controllable, and the structure is compact, the classification efficiency is high, and the operation is safe and reliable.

[0103] In some embodiments of the present invention, the crushing device 200 includes: any one of a jet mill, a mechanical mill, and a colloid mill.

[0104] Taking the jet mill as an example, the jet mill pulverizing process mainly relies on high-pressure gas to be ejected at high speed from the acceleration nozzle, so that the material obtains high-speed kinetic energy and moves at high speed in the pulverizing chamber, and the purpose of pulverizing particles is achieved through collisions between particles or between particles and the cavity wall. When the particle size becomes smaller, the particles will be separated by the airflow to the separator 300.

[0105] For example, unqualified particles separated by the separator 300 can be returned to the pulverizing chamber of the jet mill for further pulverization.

[0106] In some embodiments of the present invention, the separator 300 includes a cyclone separator, the bottom of the cyclone separator has a first material distribution port for conveying qualified materials, and the top of the cyclone separator has a second material distribution port for conveying first dust-collecting materials.

[0107] Exemplarily, the qualified material discharged from the first material distribution port can be a product of normal particle size, the particle size D1 of the qualified material satisfies: 3.0 μm≤D1≤4.0 μm, and the weight of the qualified material accounts for 0.5%-2% of the total weight of the material.

[0108] Exemplarily, the blades 20 of the cages 21 of the first air classifier and the second air classifier are arc-shaped.

[0109] In some embodiments of the present invention, the first air classifier and the second air classifier are both vertical turbine classifiers, the top of the vertical turbine classifier has a feed inlet, the bottom of the vertical turbine classifier has a coarse powder discharge port, and the side of the vertical turbine classifier is provided with a fine powder discharge port.

[0110] In some embodiments of the present invention, the first air classifier and the second air classifier are both horizontal turbine classifiers, the horizontal turbine classifier has a feed inlet at the top, a coarse powder discharge port at the bottom, and a fine powder discharge port at the side of the horizontal turbine classifier.

[0111] In the above examples, the vertical turbine classifier and the horizontal turbine classifier each have their own characteristics. In terms of classification accuracy, the vertical turbine classifier has a stable flow field, good sealing, high precision, and can ensure the product particle size; in terms of rotation speed and wear, the vertical turbine classifier has a low rotation speed, is wear-resistant, and has low energy consumption and operating costs; in terms of processing capacity, the vertical turbine classifier is suitable for small and medium-sized scales, and large-scale production requires multiple machines to be used in conjunction and occupies a large area; the horizontal turbine classifier has a larger processing capacity at the same volume power, which is conducive to efficient large-scale production; in terms of material adaptability, the horizontal turbine classifier is suitable for materials with better fluidity. Therefore, the grading and separation system 10000 of the present invention can use vertical turbine classifiers and horizontal turbine classifiers according to actual needs.

[0112] In some embodiments of the present invention, the blades 20 of the rotating cage 21 of the first air classifier and the rotating cage 21 of the second air classifier are both arc-shaped.

[0113] The cage 21 is the core component of the vortex air classifier. The shape of the blades 20 of the cage 21 has a great influence on the internal flow field of the vortex air classifier. The present invention improves the traditional blades with a rectangular cross-section into arc-shaped blades. Under the same working conditions, when the cage 21 adopts arc-shaped blades, the flow field between the blades is the most stable, no backflow phenomenon occurs at the airflow outlet between the blades, and the inertial vortex intensity is reduced.

[0114] Preferably, the installation form of the blades of the cage 21 is a staggered installation of long and short blades. Improving the cage 21 with equal-length blades to a cage 21 with staggered installation of long and short blades can effectively improve the distribution of tangential and radial velocities on the outer cylindrical surface of the cage 21, and is conducive to improving classification accuracy and reducing classification particle size. Compared with equal-length blades, the radial velocity of the airflow at the inlet of the cage 21 is reduced and the tangential velocity is increased by adopting the staggered blade form. This is because the cross-sectional area at the airflow inlet of the improved cage 21 is increased under the same air volume and rotation speed. Under the same conditions, the tangential and radial velocity distribution of the airflow in the vortex air classifier of the staggered blade cage 21 is uniform, and the velocity fluctuation is small, so fine powder particles with a narrow particle size distribution range can be obtained.

[0115] Preferably, if Figure 4 As shown, the distance between the short blade and the outer edge of the cage 21 is 3mm-7mm, preferably 4mm; the number of blades of the cage 21 is 30-35, preferably 32. The structure of the blades of the cage 21 determines the flow field inside the vortex air classifier. Therefore, under the condition of ensuring the most suitable operating parameters of the classification equipment, the classification performance can be improved by reasonably improving the structural parameters of the blades of the cage 21.

[0116] In the present invention, when the distance is less than 3mm, the standard deviations of radial and tangential velocities are larger than those at other distances, because when the air volume is constant, the velocity distribution at the outer edge of the cage 21 is mainly affected by the resistance of the airflow passing through the blades and the inertial back-vortex strength between the blades. If the surface area of ​​the blades is too small, the spatial volume of the blade channel will increase, the inertial vortex strength of the airflow between the blades will increase, and the velocity fluctuation will be large. When the distance is greater than 7mm, backflow will appear on the right side of the airflow outlet between the blades. Continuing to reduce the length of the short blades is equivalent to reducing the number of blades of the cage 21, resulting in an increase in the cross-sectional area at the airflow outlet at the inner edge of the cage 21, a decrease in pressure, an increase in backflow at the airflow outlet between the blades, and a decrease in the flow field stability; therefore, when the distance between the short blades and the outer edge of the cage 21 is 3mm-7mm, preferably 4mm, the airflow velocity distribution on the circumference of the outer edge of the cage 21 is uniform, and the flow field between the blades is stable.

[0117] Preferably, the cross section of the air guide blade is an arc. The present invention changes the traditional straight air guide blade into a curved air guide blade, and the inertial vortex between the air guide blades of the improved eddy current air classifier is relatively weak, the tangential and radial velocity distribution of the air flow between the air guide blades is more uniform, the flow field is more stable, the axial velocity is reduced, and the powder particles can be evenly distributed in the annular space, avoiding the powder particles from concentrating on the upper part of the rotating cage 21 and interfering with each other, thereby reducing the classification accuracy.

[0118] In some embodiments of the present invention, the graded ultrafine particles A (i.e., the fifth dust collecting material) account for 15%-20% of the total weight of the material, the graded ultrafine particles B (i.e., the fourth dust collecting material) account for 30%-35% of the total weight of the material, and the graded ultrafine particles C (i.e., the second dust collecting material) account for 41%-50% of the total weight of the material.

[0119] In the present invention, the proportions of the graded ultrafine particles A, ultrafine particles B and ultrafine particles C are inferred from the particle size volume distribution ratio of the scanning electron microscope (SEM), which is obtained from the measurement results of the specific embodiment. Ultrafine particles A are taken out in ton bags (such as Figure 7 ), which is directly classified as waste material for disposal, and the ultrafine particles B are taken out in ton bags (such as Figure 7 ), the ultrafine particles B after graded separation are mixed back at the mixing place. The ultrafine particles C are pneumatically transported to the batch mixing gas delivery bin (such as Figure 7 ), the ultrafine particles C after graded separation are directly blended in the finished product ribbon.

[0120] In some embodiments of the present invention, the dust collector 400 includes: a sintered plate. The sintered plate is a highly efficient dry filtering dust collecting device. After the dust-laden gas enters the dust collector 400, it passes through the sintered plate under the action of the pressure difference. There are many tiny pores on the sintered plate, and these pores are like countless tiny filter screens. When the gas passes through, the dust particles are blocked on the surface of the sintered plate because the particle size is larger than the pore diameter. For example, for ultrafine particles with a particle size in the micron or even submicron level, as long as the pore size is appropriate, they can be effectively intercepted. As the dust accumulates on the surface of the sintered plate, a dust layer is formed. This dust layer will enhance the filtering effect to a certain extent because it can further capture smaller particles. This is the so-called "surface filtration" effect.

[0121] The invention also provides a method for processing the positive electrode material.

[0122] Please refer to Figure 6 , according to the processing method of the positive electrode material of the embodiment of the present invention, it is used to process the second dust collection material, the fourth dust collection material and the fifth dust collection material separated by the grading separation system 10000 of the above embodiment. The processing method of the positive electrode material includes: directly blending the second dust collection material with the finished product of the qualified material to obtain the first mixed material; back-blending the fourth dust collection material at the mixing place and then sintering to achieve the regrowth of single crystal particles to obtain the second mixed material; and downgrading the fifth dust collection material.

[0123] That is to say, the present invention provides a method for preparing high-yield positive electrode materials, which can achieve efficient grading and separation of dust collected materials through air flow mill-assisted grading tools, and adopt a second-stage grading and separation device 2000, that is, a first air classifier, a second air classifier and a dust collector 400, to grade the dust collected materials and then reprocess them, which can significantly reduce unit consumption and improve yield.

[0124] Exemplarily, directly blending the second dust collecting material with the finished product of qualified material includes: based on the weight of the first mixed material, the blending ratio of the second dust collecting material is 30%-50%; preferably, the blending frequency of the screw ribbon is 40Hz-50Hz, and the blending time is 3h.

[0125] Exemplarily, the fourth dust collection material is back-doped and sintered at the mixing site to achieve the regrowth of single crystal particles, including: mixing the fourth dust collection material with the materials of the production line at the mixing process to obtain a mixture, wherein the materials of the production line at least include: a positive electrode material precursor, a lithium source, and an optional doping element M, that is, the mixing ratio of the doping element M is greater than or equal to 0, and the mixing ratio of the fourth dust collection material is 1wt%-5wt% based on the weight of the second mixture; sintering the obtained mixture under a process atmosphere (such as an oxygen atmosphere); coarsely crushing, finely crushing and sieving the sintered material in turn to obtain a back-doped processed material containing the crushed dust collection material of the positive electrode material.

[0126] For example, the sintering temperature is 800°C-1000°C, the sintering time is 20h-30h, the oxygen content of the process atmosphere is ≥90vol%, and the gas flow rate is 600-1300Nm 3 / h.

[0127] Exemplarily, the mixing ratio of the fourth dust collecting material is 4.1wt%-5wt%.

[0128] Exemplarily, qualified materials refer to the materials obtained by sintering the precursor of the positive electrode material with lithium, and then crushing the materials. The crushed materials are transported to the classification area of ​​the crusher by the rising airflow, and the qualified fine powder that meets the particle size requirements is screened out by the horizontally arranged classification wheel in the crusher. The qualified fine powder enters the high-efficiency cyclone separator with the airflow, and is discharged from the bottom of the cyclone separator for collection. This part of the material is the qualified material, and the coarse powder that does not meet the particle size requirements is returned to the crushing area of ​​the crusher for further crushing. The dust-containing gas in the cyclone separator is filtered and purified by the dust collector and then enters the air classifier. The finished product of qualified materials refers to the product obtained by post-processing of qualified materials. The post-processing process can be to screen and remove iron from the qualified materials to obtain the finished product of qualified materials; or to screen and remove iron from the qualified materials and then mix and sinter with the coating additives to obtain the coated product, and then screen and remove iron from the coated product to obtain the finished product of qualified materials.

[0129] Exemplarily, post-processing includes screening and removing iron from qualified materials to obtain finished products; or screening and removing iron from qualified materials, then mixing with coating additives, sintering, and then screening and removing iron from qualified materials to obtain finished coating materials.

[0130] Taking the use of a jet mill assisted classification tool as an example, a specific method for processing positive electrode materials of the present invention is described.

[0131] S1: Use the graded separation system 10000 to separate the dust collection material into three products with different particle size distributions, namely:

[0132] Ultra-ultrafine particles A with D50 < 0.9 μm, ultra-fine particles B with D50 = 0.9-1.5 μm, and ultra-fine particles C with large particles with D50 > 1.5 μm;

[0133] S2: Directly downgrading the ultra-ultrafine particles A after the graded separation.

[0134] S3: The ultrafine particles B after graded separation are back-doped at the mixing point and then sintered to achieve the regrowth of single crystal particles.

[0135] S4: The ultrafine particles C after graded separation are directly blended in the finished product ribbon.

[0136] Preferably, the determination of the D50 value in the separated material in step S1 is based on a particle size analysis method and a scanning electron microscope imaging system.

[0137] Preferably, the ultra-ultrafine particles degraded in step S2 account for 15%-20% by weight of the total dust collection material.

[0138] Preferably, in step S3, the medium-sized ultrafine particles B are first mixed with the cathode material precursor, lithium source, doping element M, etc. of the production line at the mixing process to obtain a mixture, and the medium-sized ultrafine particles B account for 1%-5% of the total weight of the mixture; the obtained mixture is sintered in an oxygen atmosphere, and the sintered material is coarsely crushed, finely crushed and sieved in sequence to obtain a mixed material containing the cathode material crushed dust collection material. The cathode material medium-sized crushed dust collection material is recycled to reduce production costs, and the prepared cathode material discharge capacity and other properties are basically consistent with normal cathode materials.

[0139] Furthermore, in step S3, the medium-sized ultrafine particles B account for 30%-35% of the total amount of the dust collection material, the back-mixing sintering temperature is 800-1000°C, the sintering time is 20-30h, and the sintering gas flow rate is 600Nm 3 / h-1300Nm 3 / h. Preferably, the sintering gas flow rate is 850Nm 3 / h-1100Nm 3 / h, more preferably, the sintering gas flow rate is 950 Nm 3 / h - 1100 Nm 3 / h. When the sintering gas flow rate meets the above conditions, the change value of the residual alkali content of the backmixing product or the mixed product can be controlled within an acceptable range.

[0140] Preferably, the backmixing ratio of the medium-sized ultrafine particles B in the mixture is 4.1 wt% - 5 wt%.

[0141] Preferably, the lithium source in the backmixing compounding material is a conventional choice in the art and can be selected from one of lithium hydroxide and lithium carbonate.

[0142] Preferably, the oxygen-containing gas is oxygen or air. To improve the sintering effect, air is selected as the oxygen-containing atmosphere.

[0143] Preferably, to control the uniformity of the oxygen-containing atmosphere during sintering, the sintering gas flow rate is controlled to be 1 m 3 / h - 8 m 3 / h, preferably 3 m 3 / h - 6 m 3 / h.

[0144] Preferably, by mass ratio, the large-sized ultrafine particles C in step S4 account for 50% of the total amount of the dust collection material.

[0145] Furthermore, the blending ratio of the large-sized ultrafine particles C to the products of the same production line batch is 30% - 50%, the blending spiral ribbon frequency is 40 Hz - 50 Hz, and the blending time is 3 h. When the blending is carried out by the large-sized particle blending treatment method, the consistency of products in different batches can be ensured, the product quality can be improved, and the electrochemical performance of the finished product test data is proved to be basically consistent with the original product and has the same market value.

[0146] The present invention also provides a cathode material.

[0147] The cathode material according to the embodiment of the present invention, the cathode material includes a compound LiNi shown in the following molecular formula x Co y Mn z M a O2, where 0 < x < 1, 0 < y < 1, 0 < z < 1, 0 ≤ a < 0.5, the cathode material includes: 50 wt% - 70 wt% of the finished product prepared by post-treatment of the qualified material separated by the classification separation system 10000; and 30 wt% - 50 wt% of the first mixture obtained by the treatment method of the cathode material; or, the cathode material includes: at least 95 wt% of the finished product prepared by post-treatment of the qualified material separated by the classification separation system, or further includes 1 wt% - 5 wt% of the second mixture obtained by the treatment method of the cathode material.

[0148] According to the positive electrode material of the present invention, the ultrafine particles are subdivided into three graded materials with particle size distribution according to the particle size difference, and the materials of different particle sizes are reasonably recycled and utilized in stages, so as to reduce the output proportion of waste materials, increase the output proportion of normal materials, and fully improve the yield of ultrafine particles with medium particle size, so as to maximize the value utilization of dust collection materials, reduce production costs, and significantly improve the utilization efficiency of raw materials.

[0149] In some embodiments of the present invention, the material crushed and separated by the graded separation system is a single crystal multi-element positive electrode material having a Ni content greater than or equal to 60%, measured in terms of molar percentage of transition metals.

[0150] Illustratively, the material crushed and separated by the grading separation system 10000 is a single crystal positive electrode material with a Ni content ranging from 62.5% to 68.3%, or the material crushed and separated by the grading separation system 10000 is a single crystal positive electrode material with a Ni content ranging from 82.4% to 89.6%.

[0151] In a first embodiment of the present invention, the Figure 2 and Figure 6 A primary material of a single crystal multi-element positive electrode material, wherein the Ni content ranges from 62.5% to 68.3%, is specifically named as X. X is crushed by a jet mill, and the obtained dust collection material is graded, separated and utilized in stages, as follows:

[0152] (1) The dust collecting bin of the cyclone separator in the air flow mill is combined with the air classifier 100 to separate the dust collected in the dust collecting bin into three products with different particle size distributions. Figure 7 , respectively, ultra-ultrafine particles with D50 less than 0.9μm, hereinafter referred to as ultrafine particles A; medium-sized ultrafine particles with D50 values ​​between 0.9μm-1.5μm, hereinafter referred to as ultrafine particles B; and large-particle ultrafine particles with D50 greater than 1.5μm, hereinafter referred to as ultrafine particles C.

[0153] (2) Directly downgrading the ultrafine particles A after graded separation.

[0154] (3) The ultrafine particles B after graded separation are back-blended and sintered at the previous process mixing place of qualified materials to obtain the back-blended material X-HC.

[0155] (4) The ultrafine particles C after graded separation are directly blended with the finished product of qualified materials to obtain the batch blended admixture X.

[0156] (5) In step (1), the mass proportion of the separated ultrafine particles A in the dust collection material X is 20%, and the mass proportion of the ultrafine particles B in the dust collection material X is 30%.

[0157] (6) In step (3), the specific sintering process is: the constant temperature zone temperature is 923°C, the kiln sintering time is 23.5h, and the sintering gas flow rate is 1100Nm 3 / h.

[0158] (7) In the present invention, in step (3), the back-doped compound includes a precursor of the positive electrode material, a lithium source and ultrafine particles B added according to the process parameter ratio, wherein the lithium source is lithium hydroxide; the ultrafine particles B may account for 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9% and 5.0% of the mass of the compound. In this embodiment, the ultrafine particles B account for 4.5wt% of the mass of the compound.

[0159] (8) In the present invention, in step (4), the blending ratio of the ultrafine particles C in the batch mixing back admixture is 45 wt%, and the mixing equipment used can be a conventional choice in the art. In this embodiment, the mixing equipment is a ribbon mixer.

[0160] In the second embodiment of the present invention, different from the first embodiment, the Ni content in the single crystal multi-element positive electrode material of this embodiment is in the range of 82.4% to 89.6%, specifically named Y, and the dust collection and graded separation and cascade utilization method of the air flow mill process is different from that of the first embodiment:

[0161] In step (1), the three products with different particle size distributions are separated, see Figure 8 , respectively, ultra-ultrafine particles with D50 less than 0.9μm, hereinafter referred to as ultrafine particles A; medium-sized ultrafine particles with D50 values ​​between 0.9μm-1.5μm, hereinafter referred to as ultrafine particles B; and large-particle ultrafine particles with D50 greater than 1.5μm, hereinafter referred to as ultrafine particles C.

[0162] In step (2), the weight ratio of the separated ultrafine particles A to the dust collecting material Y is 15%, and in step (3), the weight ratio of the separated ultrafine particles B to the dust collecting material Y is 35%.

[0163] In step (3), the specific process of sintering is: the temperature in the constant temperature zone is 830°C, the kiln sintering time is 22.5h, the sintering gas flow rate is 610-650Nm3 / h, the oxygen-containing atmosphere is oxygen, and the mixed back admixture Y-HC is obtained.

[0164] In step (4), the blending ratio of the ultrafine particles C in the batch mixed back admixture is 35 wt %, and the batch mixed back admixture Y is obtained.

[0165] Test example:

[0166] The specific steps for preparing button batteries are as follows:

[0167] (1) 10 groups of single crystal multi-element positive electrode materials X (X-001, X-002, X-003, X-004, X-005, X-006, X-007, X-008, X-009, X-010), 10 groups of mixed back admixtures X-HC (X-001-HC, X-002-HC, X-003-HC, X-004-HC, X-005-HC, X-006-HC, X-007-HC, X-008-HC, X-009-HC, X-010-HC), and batch mixed back admixtures X, 1 0 groups of single crystal multi-element positive electrode materials Y (Y-001, Y-002, Y-003, Y-004, Y-005, Y-006, Y-007, Y-008, Y-009, Y-010), 10 groups of compounded back admixtures Y-HC (Y-001-HC, Y-002-HC, Y-003-HC, Y-004-HC, Y-005-HC, Y-006-HC, Y-007-HC, Y-008-HC, Y-009-HC, Y-010-HC), and batch mixed back admixture Y were used as positive electrode materials;

[0168] (2) Weigh the above-mentioned positive electrode active material, conductive acetylene black and polyvinylidene fluoride (PVDF) in a mass ratio of 95:3:2, dissolve PVDF in an appropriate amount of N-methylpyrrolidone (NMP), and then add the mixed positive electrode active material and acetylene black powder into NMP and stir to prepare a positive electrode slurry;

[0169] (3) The positive electrode slurry is evenly coated on the aluminum foil substrate, the wet electrode is placed in a vacuum drying oven, dried at 110°C for 12 hours, and cut into positive electrode sheets;

[0170] (4) Assemble button cells in a dry vacuum glove box.

[0171] The button cell was made with the self-made positive electrode sheet as the positive electrode, the metal lithium sheet as the negative electrode, the Celgard2500 membrane as the separator, and the electrolyte of 1 mol / L LiPF6 dissolved in a solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) with a volume ratio of 1:1:1. The test conditions for the cyclic electrochemical performance were 125 cycles at 2.7-4.3V and 1C rate. The parameters of different positive electrode active materials and the data of electrochemical performance tests are shown in Figure 9-12 shown.

[0172] Figure 7 is a scanning electron microscope image of the dust collecting material X of Example 1 and the ultrafine particles A, ultrafine particles B, and ultrafine particles C produced by classification; Figure 8 The following is a scanning electron microscope image of the dust collecting material Y of Example 2 and the ultrafine particles A, ultrafine particles B, and ultrafine particles C produced by classification. Figure 7 and Figure 8 It can be seen that the positive electrode material dust collection materials of Example 1 and Example 2 are effectively separated into three ultrafine particles with different particle size distributions, and the separation method is reasonable and effective.

[0173] Depend on Fig. 9 and Fig.10 It can be seen that the materials obtained by back-blending the ultrafine particles B and blending the ultrafine particles C in the proportions of Example 1 or Example 2 can maintain the same recyclability as normal materials and are of commercial quality.

[0174] Depend on Fig.11 It can be seen that the materials mixed with the ultrafine particles B and the ultrafine particles C according to the ratios of Example 1 and Example 2 have the same physical and chemical indicators as the corresponding normal materials and are of commercial quality.

[0175] In the description of this specification, the description with reference to the terms "some embodiments", "optionally", "further" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0176] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A graded separation system, characterized in that: include: The first-stage classification crushing device comprises: a crushing device and a separator, wherein the crushing device is used to crush materials, the separator is connected to the crushing device, and the separator is used to collect the crushed materials and separate the materials into qualified materials meeting the first condition and first dust collection materials meeting the second condition; The second-stage grading and separation device includes a first air classifier, a second air classifier and a dust collector, wherein the feed port of the first air classifier is communicated with the separator, the feed port of the second air classifier is communicated with the fine powder discharge port of the first air classifier, the fine powder discharge port of the second air classifier is communicated with the dust collector, the first air classifier is used to collect the first dust material, and to separate the first dust material into a second dust material that meets a third condition and a third dust material that meets a fourth condition, the second air classifier is used to collect the third dust material, and to separate the third dust material into a fourth dust material that meets a fifth condition and a fifth dust material that meets a sixth condition, wherein the particle size of the second dust material is larger than that of the third dust material, the particle size of the fourth dust material is larger than that of the fifth dust material, and the dust collector receives the fifth dust material.

2. The graded separation system according to claim 1, characterized in that: The classifying wheel of the first air classifier is a first classifying wheel, and the classifying wheel of the second air classifier is a second classifying wheel. The rotation speed R1 of the first classifying wheel satisfies: 5897 rpm≤R1≤6268 rpm, and the rotation speed R2 of the second classifying wheel satisfies: 7255 rpm≤R1≤7584 rpm; and / or, The classifying gap G1 of the first classifying wheel satisfies: 1.43 μm ≤ G1 ≤ 1.52 μm, and the classifying gap G2 of the second classifying wheel satisfies: 1.18 μm ≤ G1 ≤ 1.24 μm, The motor of the first air classifier is a first motor, and the motor of the second air classifier is a second motor. The first motor drives the first classifying wheel to rotate, and the second motor drives the second classifying wheel to rotate. The motor frequency F1 of the first motor satisfies: 39.4HZ≤F1≤41.9HZ, and the motor frequency F2 of the second motor satisfies: 48.5HZ≤F2≤5.7HZ.

3. The graded separation system according to claim 1, characterized in that: The particle size D1 of the qualified material satisfies: 3.0 μm ≤ D1 ≤ 4.0 μm; The particle size D3 of the second dust collecting material satisfies: 1.5 μm ≤ D3 < 3.0 μm; The particle size D5 of the fourth dust collecting material satisfies: 0.9 μm ≤ D5 < 1.5 μm; The particle size D6 of the fifth dust collecting material satisfies: D6<0.9μm.

4. The graded separation system according to claim 1, characterized in that: The crushing device includes: any one of a jet mill, a mechanical mill, and a colloid mill; And / or, the separator comprises a cyclone separator, the bottom of the cyclone separator has a first material distribution opening for conveying the qualified material, and the top of the cyclone separator has a second material distribution opening for conveying the first dust-collecting material.

5. The graded separation system according to claim 1, characterized in that: The first air classifier and the second air classifier are both vertical turbine classifiers, the top of the vertical turbine classifier is provided with a feed inlet, the bottom of the vertical turbine classifier is provided with a coarse powder discharge port, and the side of the vertical turbine classifier is provided with a fine powder discharge port; And / or, the dust collector comprises a sintered plate.

6. A method for processing positive electrode materials, used for processing the second dust collection material, the fourth dust collection material and the fifth dust collection material separated by the classification separation system according to any one of claims 1 to 5, characterized in that: include: directly blending the second dust-collected material with the finished product of qualified material to obtain a first mixed material; The fourth dust collection material is back-mixed at the mixing location and then sintered to achieve regrowth of single crystal particles to obtain a second mixed material; The fifth dust collection material is downgraded.

7. The method for processing the positive electrode material according to claim 6, characterized in that: The step of directly blending the second dust collecting material with the finished product of the qualified material comprises: The blending ratio of the second dust collecting material is 30%-50% based on the weight of the first mixed material; The mixing frequency of the spiral ribbon is 40Hz-50Hz, and the mixing time is 3h.

8. The method for processing the positive electrode material according to claim 6, characterized in that: The method of back-mixing the fourth dust collecting material at the mixing location and then sintering to achieve the regrowth of single crystal particles comprises: The fourth dust collection material is mixed with the material of the production line in the mixing process to obtain a mixed material, wherein the material of the production line at least includes: a positive electrode material precursor, a lithium source and a doping element M, the mixing ratio of the doping element M is greater than or equal to 0, and the mixing ratio of the fourth dust collection material is 1wt%-5wt% based on the weight of the second mixed material; sintering the obtained mixed material under a process atmosphere; The sintered material is coarsely crushed, finely crushed and sieved in sequence to obtain the second mixed material containing the positive electrode material pulverized dust collected material.

9. The method for processing the positive electrode material according to claim 8, characterized in that: The sintering temperature is 800°C-1000°C and the sintering time is 20h-30h; And / or, the oxygen content of the process atmosphere is ≥90 vol%, and the gas flow rate is 600-1300 Nm 3 / h; And / or, the mixing ratio of the fourth dust collecting material is 4.1wt%-5wt%.

10. A positive electrode material, characterized in that: The positive electrode material includes a compound LiNi shown in the following molecular formula x Co y Mn z M a O2, where 0 <x<1,0<y<1,0<z<1,0≤a<0.5, The positive electrode material comprises: 50wt%-70wt% of a finished product prepared by post-processing qualified materials separated by a grading separation system according to any one of claims 1 to 7, and 30wt%-50wt% of a first mixed material obtained by a positive electrode material processing method according to any one of claims 8 to 12; or, The positive electrode material includes: at least 95wt% of the finished product prepared by post-processing the qualified material separated by the grading separation system described in any one of claims 1-7, or also includes 1wt%-5wt% of the second mixed material obtained by the positive electrode material processing method described in any one of claims 8-12.

11. The positive electrode material according to claim 10, characterized in that Measured in terms of molar percentage of transition metals, the material crushed and separated by the graded separation system is a single crystal multi-element positive electrode material having a Ni content greater than or equal to 60%.

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