CN112320855B - A kind of preparation method of medium-sized cobalt tetroxide - Google Patents

Abstract

The invention discloses a preparation method of medium-sized cobalt tetroxide, comprising the following steps: (1) preparing a cobalt salt solution with a cobalt ion concentration of 85g/L-95g/L; Sodium solution; adding concentration to the sodium hydroxide solution is the ammonia solution of 180g/L-200g/L, obtains mixed solution, (2) adds cobalt salt solution, mixes The solution was subjected to a synthetic reaction for 12h-15h to obtain a slurry with a target particle size; the pH of the synthetic reaction was 7.4-8.2; (3) the slurry with a target particle size was centrifugally washed with deionized water and then dried. The final target particle size slurry is calcined at 750°C-800°C to obtain medium-sized cobalt tetroxide. The invention has high production efficiency, and the obtained product has a particle size distribution span≧0.92 and good appearance.

Description

A kind of preparation method of medium-sized cobalt tetroxide

technical field

The invention belongs to the technical field of lithium ion batteries, in particular to a method for preparing medium-sized cobalt trioxide.

Background technique

The lithium-ion battery prepared with lithium cobaltate as the positive electrode material has the characteristics of light weight, large capacity, high specific energy, high working voltage, stable discharge, suitable for high current discharge, good cycle performance, and long life. It is mainly used in 3C digital field. Lithium cobalt oxide is developing in the direction of high voltage, high compaction, and high cycle performance. Therefore, the requirements for the raw material cobalt tetroxide are getting higher and higher. Co ₃ O ₄ is a functional material with special structure and performance. The preparation of cobalt tetroxide with medium particle size of span≧0.92 can meet the needs of different enterprises.

The current hydroxyl-based cobalt tetroxide preparation process has the following problems in its products: the overall particle size distribution is narrow, and (D ₉₀ -D ₁₀ )/D ₅₀ is basically below 0.8, which cannot meet different needs; when the synthesis time is short, small particles ( Micropowder) has a relatively high proportion, and the appearance of the product is poor, which has a great impact on the subsequent preparation of positive electrode materials.

Contents of the invention

The object of the present invention is to overcome the deficiencies of the above-mentioned prior art, and provide a method for preparing medium-sized cobalt trioxide with high production efficiency, product particle size distribution span≧0.92, and good shape.

The present invention adopts following technical scheme:

A method for preparing medium-sized cobalt tetroxide, characterized in that the method comprises the following steps:

(1) preparation cobalt ion concentration is the cobalt salt solution of 85g/L-95g/L; Preparation concentration is the sodium hydroxide solution of 100g/L-110g/L; To concentration is the sodium hydroxide of 100g/L-110g/L Adding concentration is the ammoniacal solution of 180g/L-200g/L in the solution, obtains mixed solution, and the volume ratio of sodium hydroxide solution and ammoniacal solution in mixed solution is 1:(0.04-0.06);

(2) Add cobalt salt solution and mixed solution in parallel to the synthesis kettle with bottom liquid to carry out synthesis reaction for 12h-15h to obtain the slurry of target particle size; cobalt salt solution is added to the feed in the synthesis kettle The flow rate is 300L/h-400L/h, the feed flow rate of the mixed solution into the synthesis tank is 300L/h-400L/h; the pH of the synthesis reaction is 7.4-8.2;

(3) The slurry with the target particle size is centrifugally washed with deionized water at 80°C-100°C and then dried at 100°C-120°C, and the slurry with the target particle size after centrifugal washing and drying is at 750°C- Calcined at 800°C for 2h-3h to obtain medium-sized cobalt tetroxide.

According to the above-mentioned preparation method of medium-sized cobalt tetroxide, it is characterized in that the cobalt salt in the cobalt salt solution in step (1) is cobalt nitrate or cobalt chloride.

According to the above method for preparing medium-sized cobalt tetroxide, it is characterized in that the pH is adjusted in stages during the synthesis reaction in step (2): the pH of the reaction for 1h-5h is 7.4-7.6, and the pH of the reaction for 10h-15h is 7.8-8.2.

According to the above-mentioned preparation method of medium-sized cobalt tetroxide, it is characterized in that the temperature of the synthesis reaction in step (2) is 74°C-76°C, and the stirring speed of the synthesis reaction is 90-100 rpm.

According to the above-mentioned preparation method of medium-sized cobalt tetroxide, it is characterized in that the bottom liquid in step (2) is hot pure water at 80°C-90°C, and the amount of bottom liquid added is 3-4 times the volume of the cobalt salt solution.

According to the preparation method of medium-sized cobalt tetroxide above, it is characterized in that the median diameter of the slurry with the target particle size in step (2) is 8.5 μm-9.5 μm.

According to the above method for preparing cobalt tetroxide with medium particle size, it is characterized in that the characteristic value of particle size distribution of cobalt tetroxide with particle size in step (3) is greater than or equal to 0.92.

Beneficial technical effects of the present invention: the present invention is suitable for the preparation of cobalt tetroxide, the precursor of lithium cobaltate battery positive electrode material, by preparing cobalt solution and alkali solution, adding large flow into the synthesis kettle in parallel, controlling temperature, flow, stirring intensity, synthesis time and pH Periodic adjustments. When the D ₅₀ reaches 8.5-9.5 μm, the steps of washing, drying and calcining can be carried out. Cobalt tetroxide prepared by this process has a wide particle size distribution and no fine powder. The particle size of the intermediate product cobalt hydroxide is: Dmin≥2.5μm, D ₁₀ : 4.5-5.5μm, D ₅₀ :8.5-9.5μm, D ₉₀ :14.0-16.0μm, Dmax≤32μm, diameter distance (D ₉₀ -D ₁₀ ) /D ₅₀ ≧0.9; the particle size distribution of cobalt tetroxide after final calcination is: Dmin≥2μm, D ₁₀ ≥4-6μm, D ₅₀ : 7.5-9μm, D _90: 12.5-15.5μm, Dmax≤30μm, diameter distance (D ₉₀ -D ₁₀ )/D ₅₀ ≧0.92. Compared with the existing preparation technology, the synthesis reaction process of the present invention adopts large-flow feed, shortens the single-pot synthesis time, and improves production efficiency; through the phased adjustment of process pH, the growth rate is controlled, the output of fine powder is eliminated, and the product form is improved. appearance. The medium-sized cobalt tetroxide product prepared by the method of the present invention has a wide particle size distribution, and the characteristic value of the particle size distribution is: (D ₉₀ -D ₁₀ )/D ₅₀ ≧0.92.

Description of drawings

Fig. 1 is the technological process schematic diagram of the inventive method;

Fig. 2 is the SEM figure of the medium particle size cobalt tetroxide product that embodiment 1 obtains;

Fig. 3 is the SEM figure after the calcination of the medium-sized cobalt tetroxide product that embodiment 1 obtains;

Fig. 4 is the SEM figure of the medium particle size cobalt tetroxide product that embodiment 2 obtains;

Fig. 5 is the SEM image of the medium-sized cobalt tetroxide product obtained in Example 2 after calcination.

Detailed ways

A kind of preparation method of cobalt trioxide of medium granularity, with the cobalt salt solution of certain concentration (low concentration) as cobalt source, sodium hydroxide solution is as precipitating agent, and ammonia solution is as complexing agent, and flow (large flow rate) joins synthesis kettle, Precisely control the pH (staged adjustment), temperature and other parameters of the process to obtain cobalt hydroxide products. After washing, drying and calcination, medium-sized cobalt tetroxide products with a span≧0.92 are obtained. Specifically include the following steps:

(1) preparation of cobalt ion concentration is the cobalt salt solution of 85g/L-95g/L; The cobalt salt in the cobalt salt solution is cobalt nitrate or cobalt chloride. Preparation concentration is the sodium hydroxide solution of 100g/L-110g/L; In the sodium hydroxide solution that concentration is 100g/L-110g/L, add the ammoniacal solution that concentration is 180g/L-200g/L, obtain mixed solution, The volume ratio of sodium hydroxide solution and ammonia solution in the mixed solution is 1:(0.04-0.06).

(2) Add a fixed volume of hot pure water into the synthesis kettle as a synthesis buffer, control the temperature of the synthesis kettle to 74°C-76°C, and the stirring speed to 90-100 rpm. Add cobalt salt solution and mixed solution to the synthesis kettle with bottom liquid in parallel to carry out synthesis reaction, set the feed flow rate of cobalt salt solution to 300L/h-400L/h, and control the pH of the synthesis reaction=7.4 -8.2, adjust the pH in stages during the synthesis reaction: the pH of the reaction for 1h-5h is 7.4-7.6, and the pH of the reaction for 10h-15h is 7.8-8.2. Stabilize the feed flow rate of the mixed solution, detect the particle size of the product after 12-15 hours of synthesis reaction, and obtain the slurry with the target particle size. The median diameter (D50) of the slurry with the target particle size is 8.5 μm-9.5 μm, and the particle size meets the requirements Indicators for follow-up procedures. The bottom liquid is hot pure water at 80°C-90°C, and the amount of the bottom liquid added is 3-4 times the volume of the cobalt salt solution. The feed flow rate of the mixed solution into the synthesis tank is 300L/h-400L/h.

(3) The slurry with the target particle size is centrifugally washed with deionized water at 80°C-100°C and then dried at 100°C-120°C, and the slurry with the target particle size after centrifugal washing and drying is at 750°C- Calcined in a rotary kiln at 800°C for 2h-3h to obtain medium-sized cobalt tetroxide. The characteristic value of the particle size distribution of medium-sized cobalt tetroxide is greater than or equal to 0.92.

Example 1

Preparation cobalt ion concentration is the cobalt salt solution of 85g/L; The cobalt salt in the cobalt salt solution is cobalt nitrate or cobalt chloride. The preparation concentration is the sodium hydroxide solution of 100g/L; Add the ammonia solution that concentration is 190g/L in the sodium hydroxide solution that concentration is 100g/L, obtain mixed solution, the volume of sodium hydroxide solution and ammonia solution in the mixed solution The ratio is 1:0.04.

A fixed volume of hot pure water was added into the synthesis kettle as a synthesis buffer, and the temperature of the synthesis kettle was controlled at 76° C. and the stirring speed was 90 rpm. Add the cobalt salt solution and the mixed solution to the synthesis kettle with the bottom liquid in parallel to carry out the synthesis reaction, set the feed flow rate of the cobalt salt solution to 300L/h, and adjust the pH of the synthesis reaction in stages: 1h-5h The pH is 7.4-7.6, and the pH of 10h-15h is 7.8-8.0. Stabilize the feed flow rate of the mixed solution, detect the particle size of the product after 12 hours of synthesis reaction, and obtain the slurry with the target particle size. The median diameter (D50) of the slurry with the target particle size is 8.5 μm-9.5 μm, and the particle size reaches the required index. Carry out subsequent procedures. The bottom liquid is hot pure water at 80-90°C, and the amount of the bottom liquid added is 3-4 times the volume of the cobalt salt solution. The feed flow rate of the mixed solution added to the synthesis tank is 300L/h.

The slurry with the target particle size is centrifugally washed with deionized water at 90°C and then dried at 100°C-120°C, and the slurry with the target particle size after centrifugal washing and drying is placed in a rotary kiln at 750°C-800°C Calcined for 2 hours to obtain medium-sized cobalt tetroxide. The characteristic value of the particle size distribution of medium-sized cobalt tetroxide is greater than or equal to 0.92. Table 1 is the particle size distribution table of the medium-sized cobalt tetroxide product obtained in Example 1. FIG. 2 is an SEM image of the medium-sized cobalt tetroxide product obtained in Example 1, and FIG. 3 is an SEM image of the medium-sized cobalt tetroxide product obtained in Example 1 after calcination.

The particle size distribution table of the medium particle size cobalt tetroxide product that the embodiment 1 of table 1 obtains

granularity D(min) D(10) D(50) D(90) D(max) (D90-D10)/D50 cobalt hydroxide 3.21 5.96 9.41 14.6 21.3 0.92 tricobalt tetroxide 3.13 5.42 8.63 13.8 24.0 0.97

Example 2

The preparation cobalt ion concentration is the cobalt salt solution of 95g/L; The cobalt salt in the cobalt salt solution is cobalt nitrate or cobalt chloride. The preparation concentration is the sodium hydroxide solution of 110g/L; Add the ammonia solution that concentration is 200g/L in the sodium hydroxide solution that concentration is 110g/L, obtain mixed solution, the volume of sodium hydroxide solution and ammonia solution in the mixed solution The ratio is 1:0.06.

A fixed volume of hot pure water was added into the synthesis kettle as a synthesis buffer, and the temperature of the synthesis kettle was controlled at 76° C. and the stirring speed was 100 rpm. Add cobalt salt solution and mixed solution to the synthesis kettle with bottom liquid in parallel flow to carry out synthesis reaction, set the feed flow rate of cobalt salt solution to 400L/h, adjust the pH in stages during the synthesis reaction: react for 1h The pH of -5h is 7.4-7.6, and the pH of reaction 10h-15h is 8.0-8.2. Stabilize the feed flow rate of the mixed solution, detect the particle size of the product after 12 hours of synthesis reaction, and obtain the slurry with the target particle size. The median diameter (D50) of the slurry with the target particle size is 8.5 μm-9.5 μm, and the particle size reaches the required index. Carry out subsequent procedures. The bottom liquid is hot pure water at 80-90°C, and the amount of the bottom liquid added is 3-4 times the volume of the cobalt salt solution. The feed flow rate that the mixed solution is added to the synthesis tank is 400L/h.

The slurry with the target particle size is centrifugally washed with deionized water at 90°C and then dried at 100°C-120°C, and the slurry with the target particle size after centrifugal washing and drying is placed in a rotary kiln at 750°C-800°C Calcined for 2 hours to obtain medium-sized cobalt tetroxide. The characteristic value of the particle size distribution of medium-sized cobalt tetroxide is greater than or equal to 0.92. Table 2 is the particle size distribution table of the medium-sized cobalt tetroxide product obtained in Example 2. Figure 4 is the SEM image of the medium-sized cobalt tetroxide product obtained in Example 2, and Figure 5 is the SEM image of the medium-sized cobalt tetroxide product obtained in Example 2 after calcination.

The particle size distribution table of the medium particle size cobalt tetroxide product that table 2 embodiment 2 obtains

granularity D(min) D(10) D(50) D(90) D(max) (D90-D10)/D50 cobalt hydroxide 3.56 6.15 9.47 15.2 22.7 0.95 tricobalt tetroxide 3.18 5.48 8.37 13.5 23.2 0.96

Claims (3)

1. a preparation method of medium-sized cobalt tetroxide, is characterized in that, described method comprises the following steps: (1) Prepare a cobalt salt solution with a cobalt ion concentration of 85g/L-95g/L; prepare a sodium hydroxide solution with a concentration of 100g/L-110g/L; prepare a sodium hydroxide solution with a concentration of 100g/L-110g/L Add an ammonia solution with a concentration of 180g/L-200g/L to the solution to obtain a mixed solution, and the volume ratio of the sodium hydroxide solution to the ammonia solution in the mixed solution is 1: (0.04-0.06); (2) Add the cobalt salt solution and the mixed solution into the synthesis kettle with the bottom liquid in a co-current manner to carry out the synthesis reaction for 12h-15h to obtain the slurry with the target particle size. The median diameter of the slurry with the target particle size is 8.5μm-9.5μm; the feed flow rate of the cobalt salt solution into the synthesis kettle is 300L/h-400L/h, and the feed flow rate of the mixed solution into the synthesis kettle is 300L/h-400L/h; the synthesis reaction The pH is 7.4-8.2; the pH is adjusted in stages during the synthesis reaction: the pH of the reaction 1h-5h is 7.4-7.6, the pH of the reaction 10h-15h is 7.8-8.2; the temperature of the synthesis reaction is 74°C-76°C, the synthesis reaction The stirring speed is 90-100 rpm; (3) Centrifugally wash the slurry with the target particle size with deionized water at 80°C-100°C and then dry it at 100°C-120°C, and then dry the slurry with the target particle size after centrifugal washing and drying at 750°C- Calcined at 800°C for 2h-3h to obtain medium-sized cobalt tetroxide; the characteristic value of particle size distribution of medium-sized cobalt tetroxide is greater than or equal to 0.92, and the characteristic value of particle size distribution is (D ₉₀ -D ₁₀ )/D ₅₀ ≥0.92. 2. The method for preparing medium-sized cobalt tetroxide according to claim 1, characterized in that the cobalt salt in the cobalt salt solution in step (1) is cobalt nitrate or cobalt chloride. 3. The method for preparing medium-sized cobalt tetroxide according to claim 1, characterized in that the bottom liquid in step (2) is hot pure water at 80°C-90°C, and the amount of bottom liquid added is 1/2 of the volume of the cobalt salt solution 3-4 times.

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