Method for adjusting laser particle size and tap density of cobalt hydroxide

Abstract

The invention discloses a method for adjusting the laser particle size and tap density of cobalt hydroxide, which comprises the following steps: by taking cobalt nitrate, sodium hydroxide and ammonia water as raw materials, quickly preparing cobalt hydroxide by means of parallel flow synthesis and step-by-step liquid adding flow adjustment in the synthesis process, and then washing and drying to obtain a cobalt hydroxide product. Tests find that under certain process conditions, the laser particle size and the tap density of the cobalt hydroxide product have a linear correspondence relationship with the numerical value of step-by-step solution flow regulation and increase during wet synthesis of cobalt hydroxide, so that the laser particle size and the tap density of the cobalt hydroxide product have a linear correspondence relationship with the numerical value of step-by-step solution flow regulation and increase during wet synthesis of cobalt hydroxide. The cobalt hydroxide laser particle size and the tap density can be accurately adjusted within the ranges of 10-15 m and 1.8-2.0 g / cm < 3 >, and the control precision reaches + / -1 m and + / -0.05 g / cm < 3 >.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion battery material preparation, and in particular relates to a method for adjusting the laser particle size and tap density of cobalt hydroxide. Background Art

[0002] Lithium cobalt oxide is the earliest commercialized positive electrode material in lithium-ion batteries. It has the advantages of high operating voltage, stable discharge, high specific energy, and good cycle performance. It is mainly used to manufacture lithium-ion battery positive electrode materials for mobile phones, laptops and other portable electronic devices.

[0003] Lithium cobalt oxide is prepared by calcining cobalt trioxide and lithium carbonate, and cobalt trioxide is generally prepared by calcining cobalt hydroxide or cobalt carbonate. Therefore, the physical and chemical preparation of cobalt hydroxide directly determines the performance of lithium cobalt oxide. Among the various indicators of cobalt hydroxide, laser particle size (D 50 ) and tap density are particularly important.

[0004] First, laser particle size is an important parameter that reflects the particle size distribution of cobalt hydroxide. By regulating the laser particle size, the size distribution of cobalt hydroxide particles can be optimized, thereby improving its physical and chemical properties. Secondly, the tap density reflects the packing density of cobalt hydroxide particles under vibration or compaction conditions. By regulating the tap density, the stacking properties of cobalt hydroxide can be optimized, thereby improving its efficiency during storage, transportation and use. Cobalt hydroxide with high tap density can save storage and transportation space and reduce costs. In addition, during the material preparation process, cobalt hydroxide with high tap density is also easier to achieve uniform mixing, which is beneficial to improving product quality and stability. In addition, regulating the laser particle size and tap density of cobalt hydroxide can also help optimize the production process and improve production efficiency. Through reasonable control means, the particle size distribution and stacking density of cobalt hydroxide can be accurately controlled, thereby meeting the performance requirements of cobalt hydroxide in different application fields. However, so far, no precise control means have been found that can accurately control the laser particle size and tap density of cobalt hydroxide. Summary of the invention

[0005] The invention aims to provide a method for adjusting the laser particle size and tap density of cobalt hydroxide, so as to guide the production of nano cobalt hydroxide and accurately control the laser particle size and tap density of cobalt hydroxide.

[0006] To achieve the above object, the present invention adopts the following technical solution: A method for adjusting the laser particle size and tap density of cobalt hydroxide comprises the following steps: 1) Preparation of cobalt hydroxide Cobalt nitrate is used as a raw material to prepare a cobalt solution with a cobalt concentration of 100±2g / L as solution A; a mixed solution of sodium hydroxide and ammonia water is prepared as solution B, wherein the concentration of the sodium hydroxide solution is 200±5g / L, the concentration of the ammonia water is 180±2g / L, and the volume ratio of the ammonia solution to the sodium hydroxide solution is 0.1; the synthesis reaction is carried out in a 30L reactor. At the beginning of the reaction, solutions A and B are added to the reactor in parallel, and the cobalt hydroxide synthesis reaction is carried out under stirring conditions; during the reaction, the flow rate of solution A is strictly controlled to be 0~ 2h: 10ml / min, 2~4h: (10+x)ml / min, 4~6h: (10+2x)ml / min, 6~8h: (10+3x)ml / min, 8~10h: (10+4x)ml / min, the flow rate of solution B is dynamically adjusted according to the reaction pH value, the reaction temperature is 75±1℃, the stirring intensity is 50Hz, the reaction pH value is 8.0~8.2, and the reaction time is 10h; then the synthetic slurry is aged, washed and dried to obtain a cobalt hydroxide product; The aging process is as follows: the aging time is 30-60 minutes, the aging temperature is 75±1°C, and the stirring intensity during aging is 50Hz; the washing equipment is a centrifuge, the filter cloth specification is 6000 mesh filter cloth, the washing liquid is deionized water with a temperature of ≥90°C, and the Na in the cobalt hydroxide after washing is ≤0.002%; the drying equipment is a flash evaporator, the drying temperature is 200-240°C, and the moisture content of the material after drying is ≤0.5%.

[0007] 2) Establish the laser particle size of cobalt hydroxide (D 50 ) and the linear relationship between the tap density In the above step 1), the range of the liquid addition flow rate x increased every 2 hours is 0~5ml / min, the prepared cobalt hydroxide laser particle size y ranges from 10~15µm, and the tap density z ranges from 1.8~2.0g / cm 3 It was found that there was a positive linear relationship between the liquid addition flow rate x increased every 2 hours and the cobalt hydroxide laser particle size y and tap density z, and the numerical relationship was consistent with y=x+10, z=0.04x+1.8; 3) Calibration error There is an error between the laser particle size y and tap density z of cobalt hydroxide calculated by the equation in step 2) above and the measured laser particle size y* and tap density z* of cobalt hydroxide. The error range is |y*-y|≤1µm, |z*-z|≤0.05g / cm 3 .

[0008] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for accurately regulating the laser particle size and tap density of cobalt hydroxide for the industry. In the process of developing cobalt hydroxide products, it is unexpectedly discovered and confirmed that there is a linear relationship between the phased increase in liquid addition flow rate and the laser particle size and tap density of cobalt hydroxide. According to the test results, a specific relationship between the laser particle size and tap density of cobalt hydroxide and the step-by-step increase in solution flow rate is obtained, and the theoretical results are close to the measured results, which proves that the laser particle size and tap density of cobalt hydroxide can be accurately regulated by relying on the relationship. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a microscopic morphology of the cobalt hydroxide prepared in Example 1.

[0010] Figure 2 This is a microscopic morphology of cobalt hydroxide prepared in Example 2.

[0011] Figure 3 This is a microscopic morphology of cobalt hydroxide prepared in Example 3. DETAILED DESCRIPTION

[0012] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] Embodiment 1 The production steps are the same as above and will not be repeated here. The specific parameters in each step are as follows: Cobalt nitrate is used as raw material, and a cobalt solution with a cobalt concentration of 100±2g / L is prepared as solution A; a mixed solution of sodium hydroxide and ammonia water is prepared as solution B, wherein the concentration of sodium hydroxide solution is 200±5g / L, the concentration of ammonia water is 180±2g / L, and the volume ratio of ammonia to alkali is 0.1; the synthesis reaction is carried out in a 30L reactor. At the beginning of the reaction, solutions A and B are added to the reactor in parallel, and the cobalt hydroxide synthesis reaction is carried out under stirring conditions. During the reaction, the flow rate of solution A is strictly controlled to be 0~2h: 10ml / min, 2~4h: 10ml / min, 4~6h: 10ml / min, 6~8h: 10ml / min, 8~10h: 10ml / min, and the flow rate of solution B is dynamically adjusted according to the reaction pH value, the reaction temperature is 75±1℃, the stirring intensity is 50Hz, the reaction pH value is 8.0~8.2, and the reaction time is 10h. Then the synthetic slurry is aged, washed, and dried to obtain a cobalt hydroxide product.

[0014] The measured laser particle size of cobalt hydroxide product is y*=9.36µm, and the tap density is z*=1.83g / cm3 .

[0015] The added liquid flow rate x is 0 ml / min every 2 hours. According to the formula y=x+10, z=0.04x+1.8, the cobalt hydroxide laser particle size y=10µm and the tap density z=1.8 g / cm 3 .

[0016] |y*-y|=|9.36-10|=0.64≤1µm, |z*-z|=|1.83-1.8|=0.03≤0.05g / cm 3 .

[0017] The microscopic morphology of the prepared cobalt hydroxide is shown in the attached Figure 1 .

[0018] Embodiment 2 The production steps are the same as above and will not be repeated here. The specific parameters in each step are as follows: Cobalt nitrate is used as raw material, and a cobalt solution with a cobalt concentration of 100±2g / L is prepared as solution A; a mixed solution of sodium hydroxide and ammonia water is prepared as solution B, wherein the concentration of sodium hydroxide solution is 200±5g / L, the concentration of ammonia water is 180±2g / L, and the volume ratio of ammonia to alkali is 0.1; the synthesis reaction is carried out in a 30L reactor. At the beginning of the reaction, solutions A and B are added to the reactor in parallel, and the cobalt hydroxide synthesis reaction is carried out under stirring conditions. During the reaction, the flow rate of solution A is strictly controlled to be 0~2h: 10ml / min, 2~4h: 12ml / min, 4~6h: 14ml / min, 6~8h: 16ml / min, 8~10h: 18ml / min, and the flow rate of solution B is dynamically adjusted according to the reaction pH value, the reaction temperature is 75±1℃, the stirring intensity is 50Hz, the reaction pH value is 8.0~8.2, and the reaction time is 10h. Then the synthetic slurry is aged, washed, and dried to obtain a cobalt hydroxide product.

[0019] The measured laser particle size of cobalt hydroxide product is y*=12.43µm, and the tap density is z*=1.91g / cm 3 .

[0020] The added liquid flow rate x is 2 ml / min every 2 hours. According to the formula y=x+10, z=0.04x+1.8, the cobalt hydroxide laser particle size y=12µm and the tap density z=1.88 g / cm 3 .

[0021] |y*-y|=|12.43-12|=0.43≤1µm, |z*-z|=|1.88-1.91|=0.03≤0.05g / cm 3 .

[0022] The microscopic morphology of the prepared cobalt hydroxide is shown in the attached Figure 2 .

[0023] Embodiment 3 The production steps are the same as above and will not be repeated here. The specific parameters in each step are as follows: Cobalt nitrate is used as raw material, and a cobalt solution with a cobalt concentration of 100±2g / L is prepared as solution A; a mixed solution of sodium hydroxide and ammonia water is prepared as solution B, wherein the concentration of sodium hydroxide solution is 200±5g / L, the concentration of ammonia water is 180±2g / L, and the volume ratio of ammonia to alkali is 0.1; the synthesis reaction is carried out in a 30L reactor. At the beginning of the reaction, solutions A and B are added to the reactor in parallel, and the cobalt hydroxide synthesis reaction is carried out under stirring conditions. During the reaction, the flow rate of solution A is strictly controlled to be 0~2h: 10ml / min, 2~4h: 15ml / min, 4~6h: 20ml / min, 6~8h: 25ml / min, 8~10h: 30ml / min, and the flow rate of solution B is dynamically adjusted according to the reaction pH value, the reaction temperature is 75±1℃, the stirring intensity is 50Hz, the reaction pH value is 8.0~8.2, and the reaction time is 10h. Then the synthetic slurry is aged, washed, and dried to obtain a cobalt hydroxide product.

[0024] The laser particle size of the cobalt hydroxide product was y*=15.68µm and the tap density z*=1.98g / cm 3 .

[0025] The added liquid flow rate x is 5 ml / min every 2 hours. According to the formula y=x+10, z=0.04x+1.8, the cobalt hydroxide laser particle size y=15µm and the tap density z=2.0 g / cm 3 .

[0026] |y*-y|=|15-15.68|=0.68≤1µm, |z*-z|=|2.0-1.98|=0.02≤0.05g / cm 3 .

[0027] The microscopic morphology of the prepared nano-cobalt hydroxide is shown in the attached Figure 3 .

[0028] It can be seen from the above Examples 1-3 that the linear relationship between the cobalt solution increasing the liquid addition flow rate in stages and the laser particle size and tap density of cobalt hydroxide discovered by the present invention is accurate and reliable. By adjusting the increase in the flow rate of the cobalt nitrate solution during the wet synthesis of cobalt hydroxide, the laser particle size and tap density of cobalt hydroxide can be adjusted to 10-15 µm and 1.8-2.0 g / cm 3 The control accuracy can reach ±1µm and ±0.05g / cm 3 .

Claims

1. A method for adjusting the laser particle size and tap density of cobalt hydroxide, characterized in that: The following steps are involved: 1) Preparation of cobalt hydroxide Cobalt nitrate is used as a raw material to prepare a cobalt solution with a cobalt concentration of 100±2g / L as solution A; a mixed solution of sodium hydroxide and ammonia water is prepared as solution B, wherein the concentration of the sodium hydroxide solution is 200±5g / L, the concentration of the ammonia water is 180±2g / L, and the volume ratio of the ammonia solution to the sodium hydroxide solution is 0.1; the synthesis reaction is carried out in a 30L reactor. At the beginning of the reaction, solutions A and B are added to the reactor in parallel, and the cobalt hydroxide synthesis reaction is carried out under stirring conditions; during the reaction, the flow rate of solution A is strictly controlled to be 0~ 2h: 10ml / min, 2~4h: (10+x)ml / min, 4~6h: (10+2x)ml / min, 6~8h: (10+3x)ml / min, 8~10h: (10+4x)ml / min, the flow rate of solution B is dynamically adjusted according to the reaction pH value, the reaction temperature is 75±1℃, the stirring intensity is 50Hz, the reaction pH value is 8.0~8.2, and the reaction time is 10h; then the synthetic slurry is aged, washed and dried to obtain a cobalt hydroxide product; 2) Establish a linear relationship between laser particle size and tap density of cobalt hydroxide In the above step 1), the range of the liquid addition flow rate x increased every 2 hours is 0~5ml / min, the prepared cobalt hydroxide laser particle size y ranges from 10~15µm, and the tap density z ranges from 1.8~2.0g / cm 3 It was found that there was a positive linear relationship between the liquid addition flow rate x increased every 2 hours and the cobalt hydroxide laser particle size y and tap density z, and the numerical relationship was consistent with y=x+10, z=0.04x+1.8; 3) Calibration error There is an error between the laser particle size y and tap density z of cobalt hydroxide calculated by the equation in step 2) above and the measured laser particle size y* and tap density z* of cobalt hydroxide. The error range is |y*-y|≤1µm, |z*-z|≤0.05g / cm 3 .

2. A method for adjusting the laser particle size and tap density of cobalt hydroxide as claimed in claim 1, characterized in that: In step 1), the aging process is as follows: the aging time is 30-60 minutes, the aging temperature is 75±1°C, and the stirring intensity during aging is 150Hz; the washing equipment is a centrifuge, the filter cloth specification is a 6000 mesh filter cloth, the washing liquid is deionized water with a temperature of ≥90°C, and the Na in the cobalt hydroxide after washing is ≤0.002%; the drying equipment is a flash evaporator, the drying temperature is 200-240°C, and the moisture content of the material after drying is ≤0.5%.

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