Preparation method of ammonia-free narrow-distribution lithium-rich manganese ternary material precursor

Abstract

The application discloses a preparation method of an ammonia-free narrow-distribution lithium-rich manganese ternary material precursor, and comprises the following specific steps: S1, a mixed salt solution of nickel sulfate, cobalt sulfate and manganese sulfate is prepared according to a molar ratio of 0.3-0.35:0.02-0.04:0.6-0.7, and the total molar concentration of the three metal ions of nickel, cobalt and manganese in the mixed salt solution is 1-3 mol / L; S2, a NaOH solution with a concentration of 6-10 mol / L and pure water are added into a reaction kettle at one time, then the mixed salt solution is continuously added into the reaction kettle at a flow rate of 6-10 L / h, and the material is subjected to stirring reaction at 40 DEG C-80 DEG C; S3, the mixed salt solution and a Na2CO3 solution with a concentration of 3-7 mol / L are mixed and added into the reaction kettle according to a ratio of 1:1-3, the pH value is maintained between 8.5-9.5, and the material is subjected to stirring reaction at 40 DEG C-80 DEG C. According to the application, the pH value can be adjusted by adding different alkali solutions without adding ammonia water, so that the lithium-rich manganese ternary precursor with good sphericity, uniform particles and large specific surface area can be prepared.

Description

Technical Field

[0001] This invention relates to a method for preparing an ammonia-free, narrow-distribution lithium-rich manganese ternary material precursor, which can obtain a lithium-rich manganese ternary precursor with good sphericity, uniform particle size, and large specific surface area by adding different alkaline solutions to adjust the pH value without adding ammonia. Background Technology

[0002] For ternary precursor products with narrow pitch (pitch = (D90-D10) / D50, and wide pitch below 1.2), a batch process is usually used. That is, during the material reaction and growth process, the solution is continuously added to the reactor until it exceeds the reactor volume. Then, a concentrator is used to concentrate the solution and continue the reaction until the material grows to the target particle size range and the reaction stops. Then, the ternary precursor product with the target physical properties of narrow pitch is obtained through centrifugation, washing, drying and other processes.

[0003] The preparation of ternary precursors typically requires the addition of complexing agents to adjust the precipitation rates of nickel, cobalt, and manganese, ensuring that the product components reach a specific molar ratio. However, ammonia is a harmful component that can have detrimental effects on human health and the environment, and its use and post-treatment increase production costs.

[0004] Therefore, the research objective of this invention is to design a method for preparing an ammonia-free, narrow-distribution lithium-rich manganese ternary material precursor that can adjust the pH value by adding different alkaline solutions to obtain a precursor with good sphericity, uniform particle size, and large specific surface area. Summary of the Invention

[0005] To address the technical problems existing in the prior art, the present invention provides a method for preparing an ammonia-free, narrow-distribution lithium-rich manganese ternary material precursor, which can effectively solve the technical problems existing in the prior art.

[0006] The technical solution of this invention is: A method for preparing an ammonia-free, narrow-distribution lithium-rich manganese ternary material precursor includes the following specific steps: S1. Prepare a mixed salt solution of nickel sulfate, cobalt sulfate, and manganese sulfate in a molar ratio of 0.3-0.35:0.02-0.04:0.6-0.7, wherein the total molar concentration of the three metal ions (nickel, cobalt, and manganese) in the mixed salt solution is 1-3 mol / L. S2, add 200-800 mL of 6-10 mol / L NaOH solution and 40-70 L of pure water to the reactor at one time, and then continuously add the mixed salt solution to the reactor at a flow rate of 6-10 L / h. The material is stirred and reacted at 40℃-80℃, and the reaction is stopped after the target particle size of 1.0±0.5 μm is reached. S3, the mixed salt solution and the Na2CO3 solution with a concentration of 3-7 mol / L are mixed and added to the reaction vessel in a ratio of 1:1-3, the pH is maintained between 8.5 and 9.5, and the material is stirred and reacted at 40℃-80℃ until the target particle size of 6±0.5μm is reached and the reaction is stopped.

[0007] The reaction processes in steps S2 and S3 are carried out under inert gas protection conditions, and nitrogen gas is introduced into the reactor at a flow rate of 3-6 m³ / h.

[0008] In the reaction process of step S3, a concentrator is used to concentrate the material in the reactor.

[0009] After step S3, step S4 is also included, in which the material after the reaction is completed is subjected to solid-liquid separation to obtain a solid, and the solid is washed and dried to obtain an ammonia-free, narrow-distribution, lithium-rich manganese ternary material product.

[0010] The reactor is equipped with a stirring mechanism, which includes a stirring shaft driven by a stirring drive motor. The stirring shaft is hollow and has several sets of corresponding winding shafts evenly distributed at different heights. The inner sides of the winding shafts are rotatably mounted on the stirring shaft, and effective flexible stirring blades are wound on the winding shafts. Corresponding pull rods are vertically mounted on the stirring shafts at the bottom of the winding shafts, and the bottom sides of the flexible stirring blades are fixed to the pull rods. The winding shafts are driven by a corresponding winding drive mechanism.

[0011] The stirring shaft is equipped with corresponding sliding rings that can be raised and lowered. The pull rods are fixed to the sliding rings respectively. The upper and lower ends of the sliding rings are respectively fixed to rubber tubes with embedded helical springs. The ends of the rubber tubes that are not connected to the sliding rings are respectively fixed to the stirring shaft through corresponding fixing ring plates.

[0012] The flexible stirring plate is provided with a plurality of corresponding material passage holes evenly distributed on it. The material passage holes are elongated holes arranged horizontally. After the winding shaft winds the flexible stirring plate, the rubber tube at the upper end of the slip ring is compressed and the rubber tube at the lower end of the slip ring is stretched. The tensile force on the flexible stirring plate is increased and the material passage cross-sectional area of ​​the material passage holes is expanded.

[0013] The take-up drive mechanism includes a drive helical gear connected to the inner end of the take-up shaft. The drive helical gears on the same set of take-up shafts are respectively meshed with the corresponding active helical gears, and the active helical gears are driven to the output shaft end of the corresponding take-up drive motor.

[0014] The winding drive motor is fixed to the top of the hollow part of the stirring shaft, and the electrical connection wire of the winding drive motor is connected to an external electrical controller through a corresponding electrical connection rotary joint.

[0015] The outer periphery of the electrical connection wire is fixedly fitted with a corresponding rigid tube, and the two ends of the rigid tube are respectively fixed to the winding drive motor and the electrical connection rotary joint.

[0016] Advantages of this invention: 1) Without adding ammonia, the present invention first adds a 6-10 mol / L NaOH solution during the nucleation stage, which is strongly alkaline and thus facilitates the formation of small-sized nuclei; then, during the growth stage, a 3-7 mol / L Na2CO3 solution is added, which is weakly alkaline and thus helps to balance the precipitation rate of nickel, cobalt and manganese, thereby effectively obtaining an ammonia-free, narrow-distribution lithium-rich manganese ternary material precursor with good sphericity, uniform particles and large specific surface area.

[0017] 2) This invention adapts and improves the stirring mechanism of the processing reactor, making its stirring area and stirring resistance adjustable. This allows for the formation of a larger stirring surface during the nucleation stage, resulting in more thorough stirring of the material and accelerating the nucleation efficiency. During the growth stage, the stirring area is reduced, and a larger material passage hole is formed for material to flow through the stirring surface. This effectively overcomes the problem of increased stirring resistance caused by increased solids content while maintaining the stirring efficiency of the material. It also significantly reduces the problem of poor material forming effect caused by excessive stirring and collision.

[0018] 3) The stirring mechanism of the present invention includes a stirring shaft driven by a corresponding stirring drive motor. The stirring shaft is hollow and has several sets of corresponding winding shafts evenly distributed at different heights. The inner sides of the winding shafts are rotatably mounted on the stirring shaft, and effective flexible stirring blades are wound on the winding shafts respectively. Corresponding pull rods are respectively mounted on the stirring shafts at the bottom of the winding shafts. The bottom sides of the flexible stirring blades are respectively fixed to the pull rods, and the pull rods are respectively fixed to corresponding slip rings. The upper and lower ends of the slip rings are respectively fixed outward to rubber tubes with embedded helical springs. The ends of the rubber tubes not connected to the slip rings are respectively fixed to the stirring shafts through corresponding fixing ring plates.

[0019] When the pull rod is in its initial position, i.e., when the rubber tube with the embedded helical spring is not under tension / compression, the stirring area of ​​the flexible stirring blade is at its maximum. When it is necessary to reduce the stirring area, i.e. when the reaction enters the growth stage, the winding shaft can be rotated to wind up the flexible stirring blade, thereby effectively adapting to the different stirring area and stirring resistance requirements of different reaction stages, so as to ensure the practical effect of the present invention.

[0020] 4) The flexible stirring plate of the present invention has multiple corresponding material passage holes evenly distributed on it. The material passage holes are elongated holes arranged laterally. After the winding shaft winds the flexible stirring plate, the rubber tube at the upper end of the slip ring is compressed, and the rubber tube at the lower end of the slip ring is stretched. The tensile force on the flexible stirring plate is increased, which expands the material passage cross-sectional area of ​​the material passage holes. This allows some solid materials to flow smoothly through the material passage holes during the stirring process. This not only effectively overcomes the problem of increased stirring resistance caused by increased solid content, but also significantly reduces the problem of poor material forming effect caused by excessive stirring and collision.

[0021] 5) By incorporating a rubber tube with an embedded helical spring, this invention not only controls the tension of the flexible stirring blades but also seals and isolates the moving area of ​​the slip ring, preventing solid materials from embedding between the slip ring and the stirring shaft and thus adversely affecting the movement of the slip ring, thereby significantly improving the practical effect of this invention.

[0022] 6) The winding drive motor of the winding drive mechanism of the present invention is fixedly connected to the top end of the hollow part of the stirring shaft, and its electrical connection wire is connected to an external electrical controller through a corresponding electrical connection rotary joint. Most importantly, a corresponding rigid tube is fixedly sleeved around the electrical connection wire, and both ends of the rigid tube are respectively fixed to the winding drive motor and the electrical connection rotary joint. With the intervention of the rigid tube, it is ensured that the electrical connection wire can rotate in a timely manner with the rotation of the winding drive motor, thereby preventing the electrical connection wire from becoming tangled during the rotation of the winding drive motor, further improving the practical effect of the present invention. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the present invention.

[0024] Figure 2 This is a schematic diagram of the reactor of the present invention.

[0025] Figure 3 This is a cross-sectional view of the reactor of the present invention.

[0026] Figure 4 This is a partial cross-sectional view of the stirring mechanism of the present invention.

[0027] Figure 5 This is a schematic diagram of the stirring mechanism of the present invention.

[0028] Figure 6 This is an exploded view of the components of the stirring mechanism.

[0029] Figure 7-8 Scanning electron microscope images (at different magnifications) of the products prepared in this invention.

[0030] In the attached diagram: 1. Reactor; 2. Stirring mechanism; 201. Stirring drive motor; 202. Stirring shaft; 203. Winding shaft; 204. Flexible stirring blade; 205. Tie rod; 3. Winding drive mechanism; 301. Drive helical gear; 302. Drive helical gear; 303. Winding drive motor; 4. Slip ring; 501. Helical spring; 5. Rubber fitting; 6. Fixed ring plate; 7. Material passage hole; 8. Electrical connection wire; 9. Electrical connection rotary joint; 10. Rigid fitting. Detailed Implementation

[0031] To facilitate understanding by those skilled in the art, the structure of the present invention will now be described in further detail with reference to the accompanying drawings: refer to Figure 1 A method for preparing an ammonia-free, narrow-distribution lithium-rich manganese ternary material precursor includes the following specific steps: S1. Prepare a mixed salt solution of nickel sulfate, cobalt sulfate and manganese sulfate in a molar ratio of 0.32:0.03:0.65, wherein the total molar concentration of the three metal ions (nickel, cobalt and manganese) in the mixed salt solution is 2 mol / L. S2, add 400 mL of 8 mol / L NaOH solution and 55 L of pure water to the reactor at once, then continuously add the mixed salt solution at a flow rate of 8 L / h. Figure 2 In the reactor 1 shown, the material is stirred and reacted at 60°C until the target particle size of 1.0±0.5μm is reached and then the reaction is stopped. S3, the mixed salt solution and the 5 mol / L Na2CO3 solution are mixed and added to the reaction vessel 1 in a ratio of 1:2, the pH is maintained between 8.5 and 9.5, and the materials are stirred and reacted at 60°C until the target particle size of 6±0.5 μm is reached and the reaction is stopped.

[0032] The reaction processes in steps S2 and S3 are carried out under inert gas protection conditions, and nitrogen gas is introduced into the reactor 1 at a flow rate of 5 m³ / h.

[0033] In the reaction process of step S3, a concentrator is used to concentrate the material in the reaction vessel 1.

[0034] After step S3, step S4 is also included, in which the material after the reaction is completed is subjected to solid-liquid separation to obtain a solid, and the solid is washed and dried to obtain an ammonia-free, narrow-distribution, lithium-rich manganese ternary material product.

[0035] This invention, without adding ammonia, firstly adds an 8 mol / L NaOH solution during the nucleation stage. Its strong alkalinity facilitates the formation of small-sized nuclei. Then, during the growth stage, a 5 mol / L Na₂CO₃ solution is added. Its weak alkalinity helps balance the precipitation rate of nickel, cobalt, and manganese, thus effectively obtaining an ammonia-free, narrow-distribution, lithium-rich manganese ternary material precursor. Scanning electron microscope images of the obtained ammonia-free, narrow-distribution, lithium-rich manganese ternary material precursor at different magnifications are shown below. Figure 7-8 As shown, it is obvious that it has good sphericity, uniform particle size, and a large specific surface area.

[0036] refer to Figure 2-6 The aforementioned reaction vessel 1 is equipped with a corresponding stirring mechanism 2. The stirring mechanism 2 includes a stirring shaft 202 driven by a corresponding stirring drive motor 201. The stirring shaft 202 is hollow and has several sets of corresponding winding shafts 203 evenly distributed at different heights. The inner sides of the winding shafts 203 are rotatably mounted on the stirring shaft 202, and effective flexible stirring blades 204 are wound on the winding shafts 203. Corresponding pull rods 205 are vertically mounted on the stirring shaft 202 at the bottom side of the winding shafts 203. The bottom sides of the flexible stirring blades 204 are fixed to the pull rods 205. The winding shafts 203 are driven by a corresponding winding drive mechanism 3.

[0037] This invention improves the design of the stirring mechanism 2 of the processing reactor 1 by making its stirring area and stirring resistance adjustable. This allows for the formation of a larger stirring surface during the nucleation stage, thereby achieving more thorough stirring of the material and accelerating the nucleation efficiency. During the growth stage, the stirring area can be reduced to maintain the stirring efficiency of the material while effectively overcoming the problem of increased stirring resistance caused by the increased solids content. It also significantly reduces the problem of poor material forming effect caused by excessive stirring and collision.

[0038] The stirring shaft 202 is equipped with corresponding sliding rings 4 that can be raised and lowered. The pull rods 205 are fixed to the sliding rings 4 respectively. The upper and lower ends of the sliding rings 4 are respectively fixed to rubber tubes 5 with embedded helical springs 501. The ends of the rubber tubes 5 that are not connected to the sliding rings 4 are respectively fixed to the stirring shaft 202 through corresponding fixing ring plates 6.

[0039] When the pull rod 205 is in the initial position, that is, when the rubber tube 5 with the embedded helical spring 501 is not in a stretched / compressed state, the stirring area of ​​the flexible stirring plate 204 is at its maximum. When it is necessary to reduce the stirring area, that is, when the reaction enters the growth stage, the winding shaft 203 can be rotated to wind up the flexible stirring plate 204, thereby effectively adapting to the different stirring area and stirring resistance requirements of different reaction stages (forming a larger stirring surface in the nucleation stage and reducing the stirring area in the growth stage), so as to ensure the practical effect of the present invention.

[0040] The flexible stirring plate 204 is provided with a plurality of corresponding material passage holes 7 evenly distributed on it. The material passage holes 7 are elongated holes arranged horizontally. After the winding shaft 203 winds up the flexible stirring plate 204, the rubber tube 5 located at the upper end of the slip ring 4 is compressed and the rubber tube 5 located at the lower end of the slip ring 4 is stretched. The tensile force on the flexible stirring plate 204 is increased and the material passage cross-sectional area of ​​the material passage hole 7 is expanded.

[0041] The present invention, through the design of the material passage hole 7 on the flexible stirring plate 204, especially during the winding process of the flexible stirring plate 204, can enlarge the material passage hole 7, thereby facilitating the smooth flow of some solid materials through the material passage hole 7 during the stirring process. This not only effectively overcomes the problem of increased stirring resistance caused by increased solid content, but also significantly reduces the problem of poor material forming effect caused by excessive stirring and collision.

[0042] By incorporating a rubber tube 5 with an embedded helical spring 501, this invention not only controls the tension of the flexible stirring blade 204 but also seals and isolates the moving area of ​​the slip ring 4. This prevents solid materials from embedding between the slip ring 4 and the stirring shaft 202 and causing adverse effects on the movement of the slip ring 4, thereby significantly improving the practical effect of this invention.

[0043] The winding drive mechanism 3 includes a drive helical gear 301 connected to the inner end of the winding shaft 203. The drive helical gears 301 on the same set of winding shafts 203 are respectively meshed with the corresponding active helical gears 302. The active helical gears 302 are respectively driven to the output shaft end of the corresponding winding drive motor 303.

[0044] The winding drive motor 303 is fixed to the top of the hollow part of the stirring shaft 202, and the electrical connection wire 8 of the winding drive motor 303 is connected to the external electrical controller through the corresponding electrical connection rotary joint 9.

[0045] The electrical connection wire 8 is surrounded by a corresponding rigid tube 10, with both ends of the rigid tube 10 fixed to the winding drive motor 303 and the electrical connection rotary joint 9, respectively. The rigid tube 10 ensures that the electrical connection wire 8 rotates in time with the winding drive motor 303, thus preventing the electrical connection wire 8 from becoming tangled during the rotation of the winding drive motor 303, further improving the practical effect of the invention.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an ammonia-free, narrow-distribution lithium-rich manganese ternary material precursor, characterized in that, The specific steps include the following: S1. Prepare a mixed salt solution of nickel sulfate, cobalt sulfate, and manganese sulfate in a molar ratio of 0.3-0.35:0.02-0.04:0.6-0.7, wherein the total molar concentration of the three metal ions (nickel, cobalt, and manganese) in the mixed salt solution is 1-3 mol / L. S2, add 200-800 mL of 6-10 mol / L NaOH solution and 40-70 L of pure water to the reactor at one time, and then continuously add the mixed salt solution to the reactor at a flow rate of 6-10 L / h. The material is stirred and reacted at 40℃-80℃, and the reaction is stopped after the target particle size of 1.0±0.5 μm is reached. S3, the mixed salt solution and the Na2CO3 solution with a concentration of 3-7 mol / L are mixed and added to the reaction vessel in a ratio of 1:1-3, the pH is maintained between 8.5 and 9.5, and the material is stirred and reacted at 40℃-80℃ until the target particle size of 6±0.5μm is reached and the reaction is stopped. The reactor is equipped with a stirring mechanism, which includes a stirring shaft driven by a stirring drive motor. The stirring shaft is hollow and has several sets of winding shafts evenly distributed at different heights. The inner sides of the winding shafts are rotatably mounted on the stirring shaft, and effective flexible stirring blades are wound on the winding shafts. Corresponding pull rods are vertically mounted on the stirring shafts at the bottom of the winding shafts, and the bottom sides of the flexible stirring blades are fixed to the pull rods. The winding shafts are driven by a corresponding winding drive mechanism. The stirring shaft is equipped with corresponding sliding rings that can be raised and lowered. The pull rods are fixed to the sliding rings respectively. The upper and lower ends of the sliding rings are respectively fixed to rubber tubes with embedded helical springs. The ends of the rubber tubes that are not connected to the sliding rings are respectively fixed to the stirring shaft through corresponding fixing ring plates. The flexible stirring plate is provided with a plurality of corresponding material passage holes evenly distributed on it. The material passage holes are elongated holes arranged horizontally. After the winding shaft winds the flexible stirring plate, the rubber tube at the upper end of the slip ring is compressed and the rubber tube at the lower end of the slip ring is stretched. The tensile force on the flexible stirring plate is increased and the material passage cross-sectional area of ​​the material passage holes is expanded.

2. The method for preparing an ammonia-free, narrow-distribution, lithium-rich manganese ternary material precursor according to claim 1, characterized in that, The reaction processes in steps S2 and S3 are carried out under inert gas protection conditions, and nitrogen gas is introduced into the reactor at a flow rate of 3-6 m³ / h.

3. The method for preparing an ammonia-free, narrow-distribution, lithium-rich manganese ternary material precursor according to claim 1, characterized in that, In the reaction process of step S3, a concentrator is used to concentrate the material in the reactor.

4. The method for preparing an ammonia-free, narrow-distribution, lithium-rich manganese ternary material precursor according to claim 1, characterized in that, After step S3, step S4 is also included, in which the material after the reaction is completed is subjected to solid-liquid separation to obtain a solid, and the solid is washed and dried to obtain an ammonia-free, narrow-distribution, lithium-rich manganese ternary material product.

5. The method for preparing an ammonia-free, narrow-distribution, lithium-rich manganese ternary material precursor according to claim 1, characterized in that, The take-up drive mechanism includes a drive helical gear connected to the inner end of the take-up shaft. The drive helical gears on the same set of take-up shafts are respectively meshed with the corresponding active helical gears, and the active helical gears are driven to the output shaft end of the corresponding take-up drive motor.

6. The method for preparing an ammonia-free, narrow-distribution, lithium-rich manganese ternary material precursor according to claim 5, characterized in that, The winding drive motor is fixed to the top of the hollow part of the stirring shaft, and the electrical connection wire of the winding drive motor is connected to an external electrical controller through a corresponding electrical connection rotary joint.

7. The method for preparing an ammonia-free, narrow-distribution, lithium-rich manganese ternary material precursor according to claim 6, characterized in that, The outer periphery of the electrical connection wire is fixedly fitted with a corresponding rigid tube, and the two ends of the rigid tube are respectively fixed to the winding drive motor and the electrical connection rotary joint.

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