Method for controlling grain size of small-granularity cobaltosic oxide in reactor
阅读说明：本技术 一种控制小粒度四氧化三钴起釜粒径大小的方法 (Method for controlling grain size of small-granularity cobaltosic oxide in reactor ) 是由 初旭 谭玉虎 汤玲花 赵宗明 李俊峰 张志龙 王景誉 马子源 于 2020-12-02 设计创作，主要内容包括：本发明公开了一种控制小粒度四氧化三钴起釜粒径大小的方法,包括以下步骤：配制钴离子浓度为108-112g/L的钴盐溶液,配制氢氧化钠溶液,配制质量百分含量为8-10％的抑制剂溶液；向氢氧化钠溶液中加入浓度为180-200g/L的氨水溶液,得到混合溶液；向加有底液的合成釜中加入混合溶液使合成釜内的pH为10-10.2,再向合成釜中加入钴盐溶液,最后向合成釜中加入抑制剂溶液,进行合成反应,得到浆料；将浆料依次进行离心洗涤、干燥、煅烧,得到小粒度四氧化三钴产品。本发明通过精确控制起釜粒径大小,使起釜粒径稳定控制在2.0-2.5μm,最终产品粒径可保证在4.0-6.0μm。(The invention discloses a method for controlling the grain size of a small-granularity cobaltosic oxide kettle, which comprises the following steps: preparing a cobalt salt solution with cobalt ion concentration of 108-112g/L, preparing a sodium hydroxide solution, and preparing an inhibitor solution with the mass percentage of 8-10%; adding ammonia water solution with the concentration of 180-200g/L into the sodium hydroxide solution to obtain mixed solution; adding the mixed solution into a synthesis kettle added with the base solution to ensure that the pH value in the synthesis kettle is 10-10.2, then adding a cobaltate solution into the synthesis kettle, and finally adding an inhibitor solution into the synthesis kettle to carry out synthesis reaction to obtain slurry; and sequentially carrying out centrifugal washing, drying and calcining on the slurry to obtain the small-granularity cobaltosic oxide product. The invention can control the grain diameter of the kettle to be 2.0-2.5 μm stably by accurately controlling the grain diameter of the kettle, and the grain diameter of the final product can be ensured to be 4.0-6.0 μm.)
1. A method for controlling the grain size of small-grain cobaltosic oxide in a reactor, which is characterized by comprising the following steps:
(1) preparing a cobalt salt solution with the cobalt ion concentration of 108g/L-112g/L, preparing a sodium hydroxide solution with the concentration of 295g/L-305g/L, and preparing an inhibitor solution with the mass percentage of 8% -10%;
(2) adding an ammonia water solution with the concentration of 180g/L-200g/L into the sodium hydroxide solution obtained in the step (1) to obtain a mixed solution; the volume ratio of the sodium hydroxide solution to the ammonia water solution is 1 (0.04-0.06);
(3) adding the mixed solution into the synthesis kettle added with the base solution to enable the pH value in the synthesis kettle to be 10-10.2, then adding the cobalt salt solution into the synthesis kettle until the pH value in the synthesis kettle is 8.4-8.5, and adding the inhibitor solution into the synthesis kettle after 30-40 min to perform synthesis reaction to obtain slurry; the process conditions of the synthesis reaction are as follows: the reaction temperature is 75-76 ℃, the reaction pH value is 8.4-8.5, and the reaction time is 21-25 h;
(4) and sequentially carrying out centrifugal washing, drying and calcining on the slurry to obtain the small-granularity cobaltosic oxide product.
2. The method for controlling the particle size of small-particle-size cobaltosic oxide in the reactor according to claim 1, wherein the base solution in the synthesis reactor in the step (3) is pure water, and the volume of the base solution is 1m3-2m3。
3. The method for controlling the grain size of the small-grain cobaltosic oxide in the reactor as claimed in claim 2, wherein the slurry in step (4) is centrifugally washed by deionized water at 80-95 ℃, the centrifugally washed slurry is dried at 100-120 ℃, and the dried slurry is calcined at 800-900 ℃ to obtain the small-grain cobaltosic oxide product.
4. The method for controlling the grain size of the small-grain cobaltosic oxide starting kettle according to claim 3, wherein the flow rate of the mixed solution added into the synthesis kettle added with the base solution in the step (3) is 150L/h to 160L/h; the flow rate of adding the cobalt salt solution into the synthesis kettle added with the base solution is 295-305L/h; the flow rate of the inhibitor solution added into the synthesis kettle with the base solution is 40L/h-60L/h.
5. The method for controlling the grain size of the small-grain cobaltosic oxide starting kettle according to claim 4, wherein the grain size of the small-grain cobaltosic oxide product in the step (4) is 4.0 μm to 6.0 μm.
6. The method for controlling the particle size of the small-particle size cobaltosic oxide starting kettle according to any one of claims 1 to 5, wherein the cobalt salt solution in the step (1) is a cobalt nitrate solution; the inhibitor solution is a strong oxidizer.
7. The method for controlling the grain size of the small-granularity cobaltosic oxide starting kettle according to claim 6, wherein the inhibitor solution in the step (1) is hydrogen peroxide.
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a method for controlling the grain size of a small-grain cobaltosic oxide starting kettle.
Background
The lithium ion battery prepared by taking lithium cobaltate as the anode material has the characteristics of light weight, large capacity, high specific energy, high working voltage, stable discharge, suitability for large-current discharge, good cycle performance, long service life and the like, and is mainly applied to the field of 3C digital codes.
Lithium cobaltate is developing towards high voltage, high compaction and high cycle performance, and thus, the requirement for the raw material cobaltosic oxide is increasing. Co3O4Is a functional material with special structure and performance, conventional Co3O4The market has faced the current situation of progressive atrophy, small particle size Co3O4The market demand is gradually highlighted. The particle size of the small-particle cobaltosic oxide is small, the particle size of the reactor determines the particle size of the product and the stability of the batch particle size, and how to prepare the small-particle cobaltosic oxide is particularly important. The existing preparation process of hydroxyl cobaltosic oxide with small granularity has the following problems: the grain diameter of the finished product is unstable, so that the grain size fluctuation of the finished product is large; the micro powder can not be eliminated, the control of the kettle-lifting process is unstable, and the granularity of the batch is unstable.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for controlling the grain size of small-grain cobaltosic oxide in the reactor, which has high production efficiency, small product grain size and good cobaltosic oxide appearance.
The purpose of the invention is realized by the following technical scheme:
a method for controlling the grain size of small-grain cobaltosic oxide in a reactor, which is characterized by comprising the following steps:
(1) preparing a cobalt salt solution with the cobalt ion concentration of 108g/L-112g/L, preparing a sodium hydroxide solution with the concentration of 295g/L-305g/L, and preparing an inhibitor solution with the mass percentage of 8% -10%;
(2) adding an ammonia water solution with the concentration of 180g/L-200g/L into the sodium hydroxide solution obtained in the step (1) to obtain a mixed solution; the volume ratio of the sodium hydroxide solution to the ammonia water solution is 1 (0.04-0.06);
(3) adding the mixed solution into the synthesis kettle added with the base solution to enable the pH value in the synthesis kettle to be 10-10.2, then adding the cobalt salt solution into the synthesis kettle until the pH value in the synthesis kettle is 8.4-8.5, and adding the inhibitor solution into the synthesis kettle after 30-40 min to perform synthesis reaction to obtain slurry; the process conditions of the synthesis reaction are as follows: the reaction temperature is 75-76 ℃, the reaction pH value is 8.4-8.5, and the reaction time is 21-25 h;
(4) and sequentially carrying out centrifugal washing, drying and calcining on the slurry to obtain the small-granularity cobaltosic oxide product.
The method for controlling the grain size of the small-grain cobaltosic oxide in the reactor is characterized in that the base solution in the synthesis reactor in the step (3) is pure water, and the volume of the base solution is 1m3-2m3。
The method for controlling the grain size of the small-grain cobaltosic oxide in the reactor is characterized in that in the step (4), the slurry is centrifugally washed by deionized water at the temperature of 80-95 ℃, the centrifugally washed slurry is dried at the temperature of 100-120 ℃, and the dried slurry is calcined at the temperature of 800-900 ℃ to obtain the small-grain cobaltosic oxide product.
The method for controlling the grain size of the small-granularity cobaltosic oxide in the reactor is characterized in that the flow rate of the mixed solution added into the synthesis reactor with the base solution in the step (3) is 150L/h-160L/h; the flow rate of adding the cobalt salt solution into the synthesis kettle added with the base solution is 295-305L/h; the flow rate of the inhibitor solution added into the synthesis kettle with the base solution is 40L/h-60L/h.
The method for controlling the grain size of the small-grain cobaltosic oxide in the reactor is characterized in that the grain size of the small-grain cobaltosic oxide product in the step (4) is 4.0-6.0 mu m.
The method for controlling the particle size of the small-particle-size cobaltosic oxide stirred tank is characterized in that the cobalt salt solution in the step (1) is a cobalt nitrate solution; the inhibitor solution is a strong oxidizer.
The method for controlling the grain size of the small-granularity cobaltosic oxide stirred tank is characterized in that the inhibitor solution in the step (1) is hydrogen peroxide.
Compared with the prior art, the invention has the beneficial technical effects that: the invention relates to a method for preparing cobaltosic oxide with small particle size in a precursor of a cathode material of a lithium cobaltite battery, which ensures that the particle size of a starting kettle is stably controlled to be 2.0-2.5 mu m by accurately controlling the particle size of the starting kettle, and the particle size of a final cobaltosic oxide product with small particle size can be ensured to be 4.0-6.0 mu m. Along with the growth of crystal nucleus, the micro powder disappearance time is about 6 hours, and the particle size rising speed is stable after 6 hours. The invention controls the adding sequence of the solution from the kettle, the pH value increment and the adding time point of the inhibitor, and stably controls various process parameters in the process, so that the finally prepared small-particle-size cobaltosic oxide product has the particle size distribution D0 more than 1 mu m, Dmin: 2-4 μm, D50: 4-6 μm, D90: 6.5-9.5 μm, Dmax: 10-12 μm.
Drawings
FIG. 1 is a schematic process flow diagram of the process of the present invention;
FIG. 2 is a diagram showing the results of the detection of the small-particle size cobaltosic oxide product obtained in the examples.
Detailed Description
Referring to fig. 1, the method for controlling the grain size of the small-grain cobaltosic oxide in the reactor comprises the following steps:
preparing a solution:
(1) preparing a cobalt salt solution with the cobalt ion concentration of 108g/L-112g/L, a sodium hydroxide solution with the concentration of 295g/L-305g/L and an inhibitor solution with the mass percentage of 8% -10% by taking cobalt salt as a raw material; all solutions were stored in a front tank for future use. The cobalt salt solution is cobalt nitrate solution. The inhibitor solution is a strong oxidant, preferably, the inhibitor solution is hydrogen peroxide.
(2) Adding an ammonia water solution with the concentration of 180g/L-200g/L into the sodium hydroxide solution obtained in the step (1) to obtain a mixed solution; the volume ratio of the sodium hydroxide solution to the ammonia water solution is 1 (0.04-0.06).
And (3) taking out the kettle for control:
(3) adding a fixed volume (1-2 m) into the synthesis kettle3) The hot pure water is used as a synthesis buffer solution, the pH value of the reactor is about 8.0, and the temperature is increased to be within the range of technological parameters. Adding a mixed solution into a synthesis kettle added with a base solution, wherein the flow rate of the mixed solution added into the synthesis kettle added with the base solution is 150L/h-160L/h, the pH value in the synthesis kettle can be rapidly increased, the pH value increment is observed at the moment, the pH value increment is controlled within the range of 0.2-0.3, when the pH value is increased to 10-10.2, a cobalt salt solution is added into the synthesis kettle, and the flow rate of the cobalt salt solution added into the synthesis kettle added with the base solution is 295L/h-305L/h; keeping the flow of the mixed solution unchanged, slowly increasing the pH value at the moment, observing the pH value increase value, adjusting the flow of the mixed solution when the pH value begins to slowly decrease so that the pH value is stabilized within the process parameter requirement range within 30min, keeping the pH value in the whole process in a stable decrease trend, avoiding the fluctuation of the pH value, ensuring that the pH value of the kettle tends to be stabilized within the required time, adding an inhibitor solution when the kettle is started for 30-40 min, and ensuring that the flow of the inhibitor solution added into the synthesis kettle added with the base solution is 40-60L/h; and adding the mixed solution, the cobalt salt solution and the inhibitor solution into a synthesis kettle from the bottom in a parallel flow mode, and carrying out synthesis reaction to obtain slurry. The process conditions of the synthesis reaction are as follows: the reaction temperature is 75-76 ℃, the reaction pH value is 8.4-8.5, and the reaction time is 21-25 h. The grain diameter is detected after the kettle is taken out for 1 hour, and the grain diameter can be stably controlled to be 2.0-2.5 mu m.
Filtering, washing and drying:
(4) and after the synthesis reaction is finished, sequentially carrying out centrifugal washing, drying and calcining on the slurry to obtain the small-granularity cobaltosic oxide product. Centrifugally washing the slurry with deionized water at 80-95 ℃, drying the centrifugally washed slurry at 100-120 ℃, and calcining the dried slurry at 800-900 ℃ to obtain a small-particle-size cobaltosic oxide product with the particle size of 4.0-6.0 microns. The finally prepared small-particle size cobaltosic oxide product has the particle size distribution of D0 more than 1 mu m, Dmin: 2-4 μm, D50: 4-6 μm, D90: 6.5-9.5 μm, Dmax: 10-12 μm.
Example 1
Preparing a cobalt nitrate solution with the cobalt ion concentration of 108g/L-112g/L, a sodium hydroxide solution with the concentration of 295g/L-305g/L and an inhibitor solution with the mass percentage of 8% -10% by taking cobalt salt as a raw material; all solutions were stored in a front tank for future use. The inhibitor solution is hydrogen peroxide.
Adding ammonia water solution with the concentration of 180g/L-200g/L into the sodium hydroxide solution to obtain mixed solution; the volume ratio of the sodium hydroxide solution to the ammonia water solution is 1 (0.04-0.06).
Adding a fixed volume (1-2 m) into the synthesis kettle3) The hot pure water is used as a synthesis buffer solution, the pH value of the reactor is about 8.0, and the temperature is increased to be within the range of technological parameters. Adding the mixed solution into a synthesis kettle added with the base solution, wherein the feeding flow is 150L/h-160L/h, the pH value in the synthesis kettle can be quickly increased, the pH value increment is observed at the moment, the pH value increment is controlled within the range of 0.2-0.3, when the pH value is increased to 10-10.2, the cobalt nitrate solution is added into the synthesis kettle, and the feeding flow is 300L/h; keeping the flow of the mixed solution unchanged, slowly increasing the pH value at the moment, observing the pH value increase value, adjusting the flow of the mixed solution when the pH value begins to slowly decrease so that the pH value is stabilized within the process parameter requirement range within 30min, keeping the pH value in the whole process in a stable decrease trend, avoiding the fluctuation of the pH value, ensuring that the pH value of the kettle tends to be stabilized within the required time, adding an inhibitor solution when the kettle is started for 30-40 min, and ensuring that the flow of the inhibitor solution added into the synthesis kettle added with the base solution is 40-60L/h; and adding the mixed solution, the cobalt salt solution and the inhibitor solution into a synthesis kettle from the bottom in a parallel flow mode, and carrying out synthesis reaction to obtain slurry. The process conditions of the synthesis reaction are as follows: the reaction temperature is 75-76 ℃, the reaction pH value is 8.4-8.5, and the reaction time is 21-25 h. The grain diameter is detected after the kettle is taken out for 1 hour, the grain diameter can be stably controlled to be 2.0-2.5 mu m, and the result is shown in table 1.
After the synthesis reaction is finished, centrifugally washing the slurry with deionized water at the temperature of 80-95 ℃, drying at the temperature of 100-120 ℃, and calcining at the temperature of 800-900 ℃ to obtain a small-granularity cobaltosic oxide product, wherein the finally prepared small-granularity cobaltosic oxide product has the granularity distribution D0 of more than 1 mu m, Dmin: 2-4 μm, D50: 4-6 μm, D90: 6.5-9.5 μm, Dmax: 10-12 μm, and the results are shown in Table 2.
TABLE 1 data sheet of small particle size cobaltosic oxide from kettle for 1 hour
Numbering
D0(μm)
D10(μm)
D50(μm)
D90(μm)
D100(μm)
CJL-TB6-T1
0.01
0.84
2.19
3.92
6.66
CJL-TB6-T2
0.36
1.14
2.22
3.92
5.91
CJL-TB6-T3
0.36
1.16
2.34
4.22
7.62
CJL-TB6-T4
0.407
1.16
2.35
4.3
7.6
CJL-TB6-T5
0.406
1.14
2.33
4.18
6.72
CJL-TB6-T6
0.406
1.09
2.30
4.23
6.72
CJL-TB6-T7
0.358
0.994
2.54
3.18
5.91
CJL-TB6-T8
0.322
1.02
2.11
3.73
5.91
TABLE 2A set of small particle size cobaltosic oxide synthesis end data table
Numbering
D0(μm)
D10(μm)
D50(μm)
D90(μm)
D100(μm)
CJL-TB6-T1
1.67
3.11
4.87
7.54
11.20
CJL-TB6-T2
1.66
2.88
4.48
6.83
9.86
CJL-TB6-T3
1.70
3.13
4.66
6.93
12.10
CJL-TB6-T4
1.71
3.61
4.81
7.29
12.60
CJL-TB6-T5
1.89
3.32
4.96
7.33
12.40
CJL-TB6-T6
1.88
3.11
4.83
7.32
9.86
CJL-TB6-T7
1.47
2.90
4.90
8.14
12.70
CJL-TB6-T8
1.48
2.96
4.99
9.31
12.70
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