Washing method of low-sulfur NCA ternary precursor

Abstract

The invention discloses a washing method of a low-sulfur NCA ternary precursor, which comprises the following specific steps: S1, organic matter washing: an organic matter solution is added into the NCA ternary precursor, and the addition amount of the organic matter solution is 90-110% of the required amount for replacing SO4 < 2->; s2, stirring and washing: stirring and washing the NCA ternary precursor added with the organic matter through stirring and washing equipment for 4-6 minutes, and then carrying out solid-liquid separation by using a suction filtration machine; and S3, stirring and washing: stirring and washing the NCA ternary precursor material obtained by stirring and washing in the step S2 by using hot water for 4-6 minutes, and then carrying out solid-liquid separation by using a suction filtration machine to obtain the low-sulfur NCA ternary precursor. According to the method, the effect of reducing the content of SO4 < 2-> in the NCA precursor can be achieved on the premise of not influencing other technical indexes of the NCA precursor.

Description

Technical Field

[0001] The present invention relates to a washing method for a low-sulfur NCA ternary precursor, which is mainly used for washing and processing the NCA ternary precursor. Background Art

[0002] In recent years, the output of lithium-ion batteries has increased rapidly and the application fields have been continuously expanded. As the market's requirements for the cycle life, fast charging performance, and energy density of lithium-ion batteries are getting higher and higher, it is necessary to continuously improve the performance of the cathode material precursor of lithium-ion batteries.

[0003] The NCA ternary precursor has advantages such as low cost, high capacity retention rate, good cycle performance, and high thermal stability. The commonly used preparation method is the liquid-phase co-precipitation controlled crystallization method. The precipitate product contains a large amount of impurities, such as Ca, Mg, Na, etc. Among them, cation impurities can be easily removed by stirring and washing, while anion impurities, such as Cl - 、SO4 2- 、NO 3- etc., especially SO4 2- , it is difficult to remove by conventional washing methods, thus affecting the cycle performance of the ternary material. The currently commonly used washing method is to use low-concentration NaOH to wash anion impurities, and its washing effect is obvious. However, since Al is an amphoteric substance, the dissolution of Al(OH)3 is easily caused during the washing process, thus affecting the performance of the NCA precursor material.

[0004] Therefore, on the premise of not affecting the performance of the NCA precursor material, designing a washing method for a low-sulfur NCA ternary precursor that can effectively reduce the SO4 2- content in the finished product of the NCA ternary precursor, thereby effectively improving the quality of the NCA ternary precursor is the research objective of the present invention. Summary of the Invention

[0005] In view of the above technical problems existing in the prior art, the present invention provides a washing method for a low-sulfur NCA ternary precursor, which can effectively solve the above technical problems existing in the prior art.

[0006] The technical solution of the present invention is as follows: A washing method for a low-sulfur NCA ternary precursor, comprising the following specific steps: S1, organic matter washing: adding an organic matter solution to the NCA ternary precursor, and the addition amount of the organic matter solution is 90-110% of the required amount for replacing SO4 2- ; S2, stirring and washing: stirring and washing the NCA ternary precursor added with the organic matter through a stirring and washing device. After the washing duration of 4-6 minutes, solid-liquid separation is carried out using a suction filter. S3. Stir and wash with water. Use hot water to stir and wash the NCA ternary precursor material obtained from the stirring and washing in step S2. After 4 - 6 minutes of water washing, use a suction filter to separate the solid and liquid to obtain a low - sulfur NCA ternary precursor.

[0007] The organic matter in step S1 is one or more of sodium malonate, sodium succinate, and sodium glutarate.

[0008] After step S3, it also includes S4 drying. Put the low - sulfur NCA ternary precursor obtained in step S3 into a corresponding oven for drying treatment.

[0009] The stirring and washing equipment used in steps S2 and S3 includes: A washing tank, which is externally connected with corresponding feed pipes, hot water inlet pipes, and discharge pipes at high and low positions respectively; A stirring drive mechanism, including a variable - speed drive motor fixedly installed on the top of the washing tank. The output shaft end of the variable - speed drive motor is downwardly connected to a stirring shaft rotatably installed in the washing tank; A number of aggregate - type stirring blades, evenly fixed on the stirring shaft. The aggregate - type stirring blades are arc - shaped and have a semi - circular cross - section. At least one corresponding guide pipe is arranged in the middle of the aggregate - type stirring blade; A washing - strengthening mechanism, including an elastic buffer on the rear side of the discharge end of the guide pipe. A plurality of corresponding liquid - permeable holes are evenly arranged on the elastic buffer. Under the agitation of the aggregate - type stirring blade, the NCA ternary precursor makes full contact with the organic matter or hot water for washing; during the washing process, the variable - speed drive motor alternately speeds up and slows down. During the speed - up process, the material is output backward along the guide pipe under the guidance of the aggregate - type stirring blade and forms a scour on the elastic buffer. After being scoured, the elastic buffer forms an accommodation cavity, and the liquid material flows backward through the liquid - permeable holes. The NCA ternary precursor forms a tumbling wash in the accommodation cavity of the deformed elastic buffer; during the speed - down process, the scouring force on the elastic buffer decreases and it restores its deformation to push the NCA ternary precursor material in the accommodation cavity outward, so as to improve the contact efficiency between the NCA ternary precursor and the organic matter or hot water.

[0010] The elastic buffer is respectively fixedly connected to the stirring shaft through corresponding connecting plates. The connecting plates are respectively provided with corresponding mounting holes at positions corresponding to the elastic buffer, and the elastic buffer is respectively fixedly connected in the corresponding mounting holes.

[0011] Elastic support rods are respectively fixedly connected in a planar spiral shape at the mounting holes, and the elastic buffer is coated and connected to the outside of the elastic support rods.

[0012] The elastic supporting rod is made of spring steel.

[0013] The liquid-permeable holes are arranged at intervals of the elastic supporting rods arranged in a plane spiral.

[0014] Advantages of the present invention: 1) The present invention washes the NCA ternary precursor with organic matter, and controls the amount of organic matter added to be SO4 2- 90-110% of the molar amount; SO4 of the NCA ternary precursor is washed by an organic solution 2- content, and then wash the Na content of the NCA ternary precursor with hot pure water to finally obtain low Na, SO4 2- The addition of organic matter can replace the SO4 contained in the NCA precursor lattice. 2- , without affecting other technical indicators of NCA precursor, to reduce SO4 in NCA precursor 2- The effect of content.

[0015] 2) The present invention also makes an adaptive improvement design to the stirring and washing equipment, which sets the aggregate stirring blade in an arc shape, sets the cross section of the aggregate stirring blade in a semicircular shape, and sets a material guide pipe in the middle of the aggregate stirring blade; then an stirring and washing enhancement mechanism is added, which includes an elastic buffer disposed on the rear side of the discharge end of the material guide pipe, and a plurality of liquid permeable holes are evenly distributed on the elastic buffer. Under the stirring action of the aggregate stirring blade, the NCA ternary precursor forms sufficient contact with organic matter or hot water for washing; and during the washing process, the variable speed drive motor alternately speeds up and slows down. During the speed-up process, the material is output backward along the material guide pipe under the guidance of the aggregate stirring blade and flushed toward the elastic buffer. After being flushed, the elastic buffer forms a receiving cavity, and the liquid material flows backward through the liquid permeable hole, and the NCA ternary precursor forms a tumbling washing in the receiving cavity of the deformed elastic buffer. This can significantly increase the kinetic energy of the NCA ternary precursor, thereby significantly increasing its contact rate with organic matter or hot water, thereby further reducing SO4 in the NCA precursor without affecting other technical indicators of the NCA precursor. 2- The effect of content.

[0016] 3) During the deceleration process of the stirring speed of the stirring washing device of the present invention, the scouring force on the elastic buffer is reduced and the deformation is restored to push the NCA ternary precursor material in the containing chamber outward, so as to further improve the contact efficiency between the NCA ternary precursor and the organic matter or hot water, thereby further reducing the SO4 in the NCA precursor without affecting other technical indicators of the NCA precursor. 2- The effect of content.

[0017] 4) The elastic buffer members of the present invention are respectively fixedly installed through corresponding connecting plates, and are respectively wrapped and connected to the outer sides of the corresponding elastic support members to ensure that they can smoothly recover their deformations during the stirring speed reduction process, and to ensure that they have sufficient elastic force during the recovery of deformations, so as to provide sufficient elastic force for the ejection of the NCA ternary precursor material, thereby ensuring the practical effect of the present invention.

[0018] 5) The liquid permeation holes of the present invention are arranged at the intervals of the elastic support members arranged in a planar spiral manner to ensure the smooth progress of the liquid permeation process, thereby further ensuring the practical effect of the present invention.

[0019] 6) After testing, the Na content of the dried NCA ternary precursor obtained after the washing treatment by the present invention does not exceed 120 ppm, and the SO4 2- content does not exceed 3500 ppm. Description of the Drawings

[0020] Figure 1 is the process flow chart of the washing process of the present invention.

[0021] Figure 2 is the structural schematic diagram of the stirring and washing equipment.

[0022] Figure 3 is the cross-sectional view of the stirring and washing equipment.

[0023] Figure 4 is the assembly structural schematic diagram of the aggregate type stirring blade and the washing and stirring strengthening mechanism.

[0024] Figure 5 is the partial enlarged view of the aggregate type stirring blade and the washing and stirring strengthening mechanism. Detailed Embodiments

[0025] For the convenience of those skilled in the art to understand, the structure of the present invention will be further described in detail below in conjunction with the accompanying drawings: Embodiment 1 Refer to Figures 1-5 , a washing method for a low-sulfur NCA ternary precursor, including the following specific steps: S1. Organic matter washing: Add sodium succinate solution to 100 Kg of NCA ternary precursor, and the addition amount of the sodium succinate solution is 110% of the amount required to replace SO42-. S2. Stirring and washing: Stir and wash the NCA ternary precursor added with organic matter through the stirring and washing equipment. After 5 minutes of washing duration, use a suction filter for solid-liquid separation. S3, stirring and washing, using hot water to stir and wash the NCA ternary precursor material obtained by stirring and washing in step S2, after washing for 5 minutes, using a suction filter to separate the solid and liquid to obtain a low-sulfur NCA ternary precursor; S4, drying, putting the low-sulfur NCA ternary precursor obtained in step S3 into a corresponding oven for drying.

[0026] The present invention washes the NCA ternary precursor with organic matter, and controls the amount of organic matter added to be SO4 2- 110% of the molar amount; SO4 of the NCA ternary precursor is washed by an organic solution 2- content, and then wash the Na content of the NCA ternary precursor with hot pure water to finally obtain low Na, SO4 2- The addition of organic matter can replace the SO4 contained in the NCA precursor lattice. 2- , without affecting other technical indicators of NCA precursor, to reduce SO4 in NCA precursor 2- The effect of content.

[0027] The stirring washing equipment used in steps S2 and S3 includes: A washing tank 1, wherein the washing tank 1 is connected to the outside with corresponding feed pipes 101, hot water inlet pipes 102, and discharge pipes 103 according to height; The stirring drive mechanism 2 comprises a variable speed drive motor 201 fixedly mounted on the top of the washing tank 1, and the output shaft end of the variable speed drive motor 201 is downwardly connected to a stirring shaft 202 rotatably mounted in the washing tank 1; A plurality of aggregate stirring blades 3 are evenly distributed and fixed on the stirring shaft 202. The aggregate stirring blades 3 are arranged in an arc shape and their cross-section is arranged in a semicircular shape. At least one corresponding material guide pipe 301 is arranged in the middle of the aggregate stirring blades 3. The stirring and washing strengthening mechanism 4 includes an elastic buffer 401 disposed at the rear side of the discharge end of the material guiding pipe 301. A plurality of corresponding liquid permeating holes 5 are evenly distributed on the elastic buffer 401. Under the agitation of the aggregate stirring blades 3, the NCA ternary precursor makes full contact with the organic matter or hot water for washing. During the washing process, the variable speed drive motor 201 alternately performs speed increasing and speed decreasing actions. During the speed increasing process, the material is output backward along the material guiding pipe 301 under the guidance of the aggregate stirring blades 3 and forms a scouring on the elastic buffer 401. After being scoured, the elastic buffer 401 forms a receiving cavity, and the liquid material flows backward through the liquid permeating holes 5. The NCA ternary precursor forms a tumbling cleaning in the receiving cavity of the deformed elastic buffer 401. During the speed decreasing process, the scouring force on the elastic buffer 401 decreases and it recovers its deformation to push the NCA ternary precursor material located in the receiving cavity outward, so as to improve the contact efficiency between the NCA ternary precursor and the organic matter or hot water.

[0028] The present invention also makes an adaptive improvement design for the stirring and washing equipment. The aggregate stirring blades 3 are arranged in an arc shape and the cross-section of the aggregate stirring blades 3 is in a semi-circular shape, and a material guiding pipe 301 is arranged in the middle of the aggregate stirring blades 3. Then, a stirring and washing strengthening mechanism 4 is added, which includes an elastic buffer 401 disposed at the rear side of the discharge end of the material guiding pipe 301, and a plurality of liquid permeating holes 5 are evenly distributed on the elastic buffer 401. Under the agitation of the aggregate stirring blades 3, the NCA ternary precursor makes full contact with the organic matter or hot water for washing. During the washing process, the variable speed drive motor 201 alternately performs speed increasing and speed decreasing actions. During the speed increasing process, the material is output backward along the material guiding pipe 301 under the guidance of the aggregate stirring blades 3 and forms a scouring on the elastic buffer 401. After being scoured, the elastic buffer 401 forms a receiving cavity, and the liquid material flows backward through the liquid permeating holes 5. The NCA ternary precursor forms a tumbling cleaning in the receiving cavity of the deformed elastic buffer 401. Thereby, the kinetic energy of the NCA ternary precursor is greatly increased, so as to greatly increase its contact rate with the organic matter or hot water, and further, on the premise of not affecting other technical indicators of the NCA precursor, achieve the effect of reducing the content of SO4 2- content.

[0029] When the stirring speed of the stirring and washing equipment of the present invention is in the speed decreasing process, the scouring force on the elastic buffer 401 decreases and it recovers its deformation to push the NCA ternary precursor material located in the receiving cavity outward, so as to further improve the contact efficiency between the NCA ternary precursor and the organic matter or hot water, and further, on the premise of not affecting other technical indicators of the NCA precursor, achieve the effect of reducing the content of SO4 2- content.

[0030] The elastic buffer members 401 are respectively fixedly connected to the stirring shaft 202 through corresponding connecting plates 402. The connecting plates 402 are respectively provided with corresponding mounting holes 6 at positions corresponding to the elastic buffer members 401, and the elastic buffer members 401 are respectively fixedly connected in the corresponding mounting holes 6.

[0031] Corresponding elastic support rods 403 are fixedly connected in a planar spiral manner at the mounting holes 6, and the elastic buffer members 401 are wrapped and connected to the outer sides of the elastic support rods 403. The elastic support rods 403 are made of spring steel.

[0032] The elastic buffer members 401 of the present invention are respectively fixedly installed through corresponding connecting plates 402, and are respectively wrapped and connected to the outer sides of the corresponding elastic support rods 403 to ensure that they can smoothly recover their deformation during the stirring speed reduction process, and ensure that they have sufficient elastic force during the process of recovering deformation, so as to provide sufficient elastic force for the ejection of the NCA ternary precursor material, thereby ensuring the practical effect of the present invention.

[0033] The liquid permeation holes 5 are arranged at the intervals of the elastic support rods 403 arranged in a planar spiral manner to ensure the smooth progress of the liquid permeation process, thereby further ensuring the practical effect of the present invention.

[0034] After testing, the Na content of the dried NCA ternary precursor obtained after the washing treatment by the present invention is 115 ppm, and the SO4 2- content is 3210 ppm.

[0035] Example Two The difference between this example and Example One is that the organic solution used is sodium malonate solution, and the Na content of the dried NCA ternary precursor obtained after its washing treatment is 117 ppm, and the SO42- content is 3107 ppm.

[0036] It should be noted that the implementation principles and technical effects generated in this example are the same as those in Example One. For the sake of brief description, for the parts not mentioned in this example, reference can be made to the corresponding content in Example One.

[0037] Example Three The difference between this example and Example One is that the organic solution used is sodium glutarate solution, and the Na content of the dried NCA ternary precursor obtained after its washing treatment is 110 ppm, and the SO42- content is 2998 ppm.

[0038] It should be noted that the implementation principles and technical effects generated in this example are the same as those in Example One. For the sake of brief description, for the parts not mentioned in this example, reference can be made to the corresponding content in Example One.

[0039] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A washing method for a low-sulfur NCA ternary precursor, characterized in that, The specific steps include: S1, Organic matter washing: Add an organic matter solution to the NCA ternary precursor, and the addition amount of the organic matter solution is 90-110% of the required amount to replace SO4 2- ; S2, stirring and washing, stirring and washing the NCA ternary precursor added with organic matter by a stirring and washing device, after washing for 4-6 minutes, using a suction filter to separate the solid and liquid; S3, stirring and washing, using hot water to stir and wash the NCA ternary precursor material obtained by stirring and washing in step S2, after washing for 4-6 minutes, using a suction filter to separate the solid and liquid to obtain a low-sulfur NCA ternary precursor.

2. The washing method of a low-sulfur NCA ternary precursor according to claim 1, wherein The organic matter in step S1 is one or more of sodium malonate, sodium succinate and sodium glutarate.

3. The washing method of a low-sulfur NCA ternary precursor according to claim 2, characterized in that, The step S3 also includes drying in S4, wherein the low-sulfur NCA ternary precursor obtained in step S3 is put into a corresponding oven for drying.

4. The washing method of a low-sulfur NCA ternary precursor according to claim 1, characterized in that, The stirring washing equipment used in steps S2 and S3 includes: A washing tank (1), wherein the washing tank (1) is externally connected with corresponding feed pipes (101), hot water inlet pipes (102), and discharge pipes (103) at different heights; The stirring drive mechanism (2) comprises a variable speed drive motor (201) fixedly mounted on the top of the washing tank (1), wherein the output shaft end of the variable speed drive motor (201) is connected to a stirring shaft (202) rotatably mounted in the washing tank (1) in a downwardly driving manner; A plurality of aggregate-type stirring blades (3) are evenly distributed and fixedly connected to the stirring shaft (202); the aggregate-type stirring blades (3) are arranged in an arc shape and their cross-sections are arranged in a semicircular shape; at least one corresponding material guide pipe (301) is arranged in the middle of the aggregate-type stirring blades (3); The stirring and washing enhancing mechanism (4) comprises an elastic buffer (401) disposed at the rear side of the discharge end of the material guide pipe (301), wherein the elastic buffer (401) is evenly provided with a plurality of corresponding liquid permeable holes (5), and the NCA ternary precursor is fully contacted with the organic matter or hot water under the stirring action of the aggregate stirring blade (3) to be washed; during the washing process, the variable speed drive motor (201) alternately increases and decreases the speed, and during the speed increase process, the material is guided by the aggregate stirring blade (3) along the material guide pipe (301). 1) outputting backwards and flushing the elastic buffer (401), the elastic buffer (401) being flushed to form a receiving cavity, the liquid material flowing out backwards through the liquid permeable hole (5), and the NCA ternary precursor tumbling and cleaning in the receiving cavity of the deformed elastic buffer (401); during the deceleration process, the flushing force on the elastic buffer (401) is reduced and the deformation is restored, so as to push the NCA ternary precursor material in the receiving cavity outwards, so as to improve the contact efficiency between the NCA ternary precursor and the organic matter or hot water.

5. The washing method of a low-sulfur NCA ternary precursor according to claim 4, characterized in that, The elastic buffer members (401) are fixedly connected to the stirring shaft (202) via corresponding connecting plates (402), the connecting plates (402) are respectively provided with corresponding mounting holes (6) at positions corresponding to the elastic buffer members (401), and the elastic buffer members (401) are respectively fixedly connected in the corresponding mounting holes (6).

6. The washing method of a low-sulfur NCA ternary precursor according to claim 5, characterized in that, At the installation holes (6), corresponding elastic support members (403) are fixedly connected in a planar spiral shape, and the elastic buffer member (401) is wrapped and connected to the outside of the elastic support members (403).

7. The washing method of a low-sulfur NCA ternary precursor according to claim 6, wherein, The elastic support members (403) are made of spring steel.

8. A washing method for a low-sulfur NCA ternary precursor according to claim 7, characterized in that, The liquid permeable holes (5) are arranged at intervals of the elastic support members (403) arranged in a planar spiral shape.

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