Cobalt tetroxide with small particle size and narrow distribution, preparation method and application thereof

Abstract

The present invention provides a method for preparing cobalt tetroxide with small particle size and narrow distribution, comprising the following steps: preparing a raw material liquid and a dispersant solution; a synthetic reaction; washing, filtering and drying the product; and a calcination treatment. In the early stage of wet synthesis, the present invention uses sodium dodecyl sulfate as a dispersant to prepare a dispersant solution, and introduces it and the raw material liquid into the reaction vessel at the same time according to a certain flow ratio, thereby effectively preventing the agglomeration of cobalt tetroxide particles during the preparation process, and obtaining a cobalt tetroxide product with small particles and good consistency. The preparation method provided by the present invention has a simple process, is easy to operate, and is suitable for large-scale production; compared with conventional preparation methods, the reaction time of the present invention is shorter, which can improve production efficiency, reduce energy consumption, and effectively avoid the introduction of impurities during a long reaction process. The cobalt tetroxide with small particle size and narrow distribution prepared by the present invention has broad application prospects in lithium-ion battery positive electrode materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion battery materials, and in particular relates to cobalt tetroxide with small particle size and narrow distribution, and a preparation method and application thereof. Background Art

[0002] Lithium cobalt oxide, a key cathode material for lithium-ion batteries, is widely used in consumer electronics such as laptops, mobile phones, and digital cameras due to its high energy density. With the continuous advancement of technology, people have higher demands for the battery life and charging speed of electronic products. Therefore, there is an urgent need to develop lithium cobalt oxide with higher capacity and higher charge rates. Currently, the tap density of lithium cobalt oxide can be increased by mixing large and small cobalt oxide particles, thereby improving the energy density of lithium-ion batteries.

[0003] However, small particles of cobalt tetroxide often have problems such as severe particle agglomeration and uneven particle size distribution during the preparation process. Traditional preparation methods are difficult to effectively control the particle size of cobalt tetroxide, and the preparation process is complicated and costly.

[0004] Based on this, developing a method for preparing cobalt tetroxide with small particle size and narrow distribution that has a simple and efficient preparation process has important practical significance and is also a technical problem that needs to be solved urgently. Summary of the Invention

[0005] One of the objectives of the present invention is to provide a method for preparing cobalt tetroxide with small particle size and narrow distribution, which has a simple and efficient preparation process.

[0006] A second object of the present invention is to provide cobalt trioxide with small particle size and narrow distribution.

[0007] The third object of the present invention is to provide a method for applying cobalt trioxide with small particle size and narrow distribution in lithium ion batteries.

[0008] The technical solution adopted by the present invention to achieve one of the objectives is to provide a method for preparing cobalt trioxide with small particle size and narrow distribution, comprising the following steps:

[0009] S1. Dissolve a cobalt salt and a bicarbonate salt in water to obtain a first solution having a cobalt ion concentration of 110-140 g / L and a second solution having a bicarbonate ion concentration of 220-260 g / L; dissolve sodium lauryl sulfate in water to obtain a dispersant solution having a concentration of 0.1-0.2 mol / L;

[0010] S2. Using a reaction vessel with a double-layer stirring device, add water and the second solution to submerge the bottom stirring device, and heat the reaction vessel to 40-45° C. under stirring;

[0011] S3. Simultaneously adding the first solution, the second solution, and the dispersant solution into a reaction vessel, controlling the flow ratio of the first solution to the dispersant solution to be (32-38):(5-6), adjusting the flow rate of the second solution to control the pH value of the reaction system to be 7.0-7.9, and reacting at 40-45° C. for 25-30 hours to obtain a synthetic slurry;

[0012] S4. The synthetic slurry is washed, filtered and dried to obtain cobalt carbonate; the cobalt carbonate is calcined at high temperature to obtain cobalt trioxide with small particle size and narrow distribution.

[0013] The overall concept of the present invention is as follows:

[0014] In order to prepare a cobalt oxide product with a small particle size and narrow distribution, the present invention adopts a method of simultaneously introducing a reaction solution and a dispersant solution in a certain proportion in the initial stage of wet synthesis to prepare cobalt oxide. In the initial stage of wet synthesis, the substances in the system are in a relatively uniform mixed state, and the dispersant can be fully mixed with the reactants in the entire reaction system, so that the particles always maintain good dispersibility during the synthesis process and avoid local agglomeration. The method of adding a dispersant used in the present invention not only has a better dispersion effect and is conducive to obtaining a product with a better uniform particle size distribution consistency, but also reduces the post-processing process and saves cost.

[0015] In addition, the present invention separately prepares a first solution containing cobalt ions, a second solution containing bicarbonate, and a dispersant solution. Compared with directly mixing the above raw materials to prepare the reaction raw material liquid, this avoids some unnecessary pre-reactions that occur after the dispersant solution and the cobalt solution are mixed due to mutual contact during the raw material preparation stage. Under subsequent appropriate reaction temperature and rotation speed conditions, the two are simultaneously introduced into the reaction system at a certain flow ratio, so that the reaction proceeds according to the expected route, ensuring a narrow distribution and consistency of product particle size.

[0016] Furthermore, in the present invention, sodium dodecyl sulfate (SDS) was selected as the dispersant after extensive experimentation and comparison. Compared with other dispersants, SDS maintains good dispersion across a wide pH range, making it more suitable for the reaction system of the present invention. Furthermore, SDS has a relatively simple synthesis process, is readily available from a wide range of raw materials, and has a relatively low production cost, making it affordable and suitable for large-scale production and cost-effective promotion and application.

[0017] Furthermore, in step S1 of the present invention, a first solution having a cobalt ion concentration of 110-140 g / L and a second solution having a bicarbonate ion concentration of 220-260 g / L are prepared. Compared with conventional preparation methods, the present invention increases the concentration of the raw materials in the reaction solution. The high concentration of the reaction raw materials can accelerate the seed crystal generation rate and seed crystal quantity, effectively reducing the starting particle size.

[0018] Furthermore, in the above preparation method, controlling the amount of reaction solution and dispersant within a reasonable range can avoid problems such as uneven distribution of agglomeration caused by too small particles. After a large number of experiments and explorations, based on the premise that the concentration of the first solution of cobalt ions is 110-140g / L, the concentration of the dispersant solution is set to 0.1-0.2mol / L, and the flow ratio of the first solution to the dispersant solution is controlled to (32-38): (5-6) during the reaction feeding stage to ensure that the product particle size is small and evenly distributed, maintaining higher consistency. When the dispersant amount is higher than the above range, it will excessively inhibit the growth and aggregation of particles, resulting in particles with too small a particle size; when the dispersant amount is lower than the above range, the ideal dispersion effect cannot be achieved.

[0019] Furthermore, the present invention uses a reaction container with a double-layer stirring device, which increases mechanical force by utilizing the double-layer stirring to prevent the particles from being too small and thus being connected.

[0020] Furthermore, in step S1, the cobalt salt is selected from cobalt chloride and / or cobalt sulfate; and the bicarbonate is selected from ammonium bicarbonate and / or sodium bicarbonate.

[0021] Furthermore, in step S2, the volume ratio of water to the second solution is (50-55):(5-8).

[0022] Furthermore, in step S2, the stirring speed is 180-250 rpm, and the speeds of the stirring devices of the upper layer and the bottom layer are kept consistent.

[0023] Preferably, in step S3, the flow rate of the first solution is 320-380 L / h, and the flow rate of the dispersant solution is 50-60 L / h.

[0024] Furthermore, in step S3, the feed mass ratio of the second solution to the first solution per unit time is (3-5): 1. In the present invention, the pH of the reaction system is controlled by adjusting the flow rate of the second solution containing bicarbonate to ensure normal growth of the grains.

[0025] Furthermore, in step S4, the solvent used for washing is ammonium bicarbonate solution, and the temperature of the drying treatment is 80-100°C.

[0026] Furthermore, the high temperature calcination treatment is performed at a temperature of 680-750° C. and for a time of 3-5 hours. Under such conditions, the product obtained by calcination treatment has high crystallinity and a smooth surface without cracks.

[0027] The technical solution adopted by the present invention to achieve the second purpose is: to provide cobalt tetroxide with small particle size and narrow distribution, which is prepared by the preparation method according to one of the purposes of the present invention.

[0028] Furthermore, the particle size D50 of the cobalt trioxide with small particle size and narrow distribution is 3.296-3.538 μm, and the consistency is 0.216-0.418.

[0029] The technical solution adopted by the present invention to achieve the third purpose is to provide a use of the small particle size and narrow distribution cobalt tetroxide according to one of the purposes of the present invention in a lithium ion battery.

[0030] Furthermore, the small, narrowly distributed cobalt oxide produced by the present invention is mixed with larger cobalt oxide particles to increase the tap density of lithium cobalt oxide, thereby improving the energy density of lithium-ion batteries. The narrow particle size distribution of the small cobalt oxide provided by the present invention allows for a more uniform stress distribution within the material during charge and discharge, reducing local stress concentration and structural damage caused by particle size differences. This helps improve the cycling stability of lithium cobalt oxide and thus prolongs the battery's service life.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The method for preparing cobalt tetroxide with small particle size and narrow distribution provided by the present invention uses a specific dispersant sodium dodecyl sulfate (SDS) to prepare a dispersant solution in the early stage of wet synthesis, and adds it to the reaction container simultaneously with the reaction raw material liquid according to a certain flow ratio. This can effectively prevent the agglomeration of cobalt tetroxide particles during the preparation process, and obtain a cobalt tetroxide product with small particles and good consistency.

[0033] (2) The method for preparing cobalt trioxide with a small particle size and narrow particle distribution provided by the present invention is simple, easy to operate, and suitable for large-scale production. Compared with conventional preparation methods, the present invention has a shorter reaction time, which can improve production efficiency and reduce energy consumption. It can also effectively avoid the introduction of impurities during the long reaction process, thereby ensuring the purity of the product.

[0034] (3) The small-particle cobalt tetroxide provided by the present invention has the advantage of a narrow particle size distribution. When used in the positive electrode material of lithium-ion batteries, the internal stress distribution of the material is more uniform during the charge and discharge process, reducing the local stress concentration and structural damage caused by the difference in particle size, which helps to improve the cycle stability of lithium cobalt oxide and thus extend the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the XRD pattern of cobalt tetroxide prepared in Example 1 of the present invention;

[0036] Figure 2 This is a particle size distribution diagram of cobaltous oxide prepared in Example 1 of the present invention;

[0037] Figure 3 This is the particle size distribution diagram of cobaltous oxide prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0040] The present invention provides a method for preparing cobalt trioxide with small particle size and narrow distribution, comprising the following steps:

[0041] Step 1: Dissolving a cobalt salt and a bicarbonate salt in water respectively to obtain a first solution having a cobalt ion concentration of 110-140 g / L and a second solution having a bicarbonate ion concentration of 220-260 g / L; dissolving sodium lauryl sulfate in water to obtain a dispersant solution having a concentration of 0.1-0.2 mol / L; wherein the cobalt salt is selected from cobalt chloride and / or cobalt sulfate; and the bicarbonate salt is selected from ammonium bicarbonate and / or sodium bicarbonate;

[0042] Step 2: Using a reaction vessel with a double-layer stirring device, water and a second solution are added to submerge the bottom stirring device, and the volume ratio of water to bicarbonate solution is controlled to be (50-55):(5-8), and the reaction vessel is heated to 40-45°C while stirring at a speed of 180-250 rpm;

[0043] Step 3: Add the first solution, the second solution and the dispersant solution into the reaction vessel simultaneously, with the flow rate of the first solution being 320-380 L / h and the flow rate of the dispersant solution being 50-60 L / h. Adjust the flow rate of the second solution so that the pH value of the reaction system is controlled at 7.0-7.9, and react at 40-45° C. for 25-30 hours to obtain a synthetic slurry;

[0044] Step 4: The synthetic slurry is washed with ammonium bicarbonate solution, filtered, and dried at 80-100° C. to obtain cobalt carbonate; the cobalt carbonate is placed under 680-750° C. and calcined at high temperature for 3-5 hours to obtain cobalt tetroxide with small particle size and narrow distribution.

[0045] The present invention will be further described below with reference to specific examples, but they are not intended to limit the present invention.

[0046] The main parameters and experimental conditions of the preparation process of each embodiment of the present invention and the comparative example are shown in Table 1 below:

[0047] Table 1

[0048]

[0049] Example 1

[0050] This embodiment provides a method for preparing cobalt trioxide with small particle size and narrow distribution, comprising the following steps:

[0051] Step 1: Dissolve cobalt chloride hexahydrate and ammonium bicarbonate in water to obtain a first solution having a cobalt ion concentration of 130 g / L and a second solution having a bicarbonate ion concentration of 260 g / L; dissolve sodium lauryl sulfate in water to obtain a dispersant solution having a concentration of 0.1 mol / L;

[0052] Step 2: Using a reaction vessel with a double-layer stirring device, add 550L of water and 50L of ammonium bicarbonate solution as the base liquid into the reactor and heat it to 41°C;

[0053] Step 3: The first solution, the second solution, and the dispersant solution were added to the reaction vessel simultaneously. The flow rate of the cobalt solution was strictly controlled to 320 L / h, and the flow rate of the dispersant solution was 55 L / h. The flow rate of the second solution was adjusted to control the pH value of the reaction system to about 7.2. The reaction was carried out at a temperature of 41° C. and a rotation speed of 220 rpm for 30 hours to obtain a synthetic slurry.

[0054] Step 4: The synthetic slurry is washed and filtered with a 22 g / L ammonium bicarbonate solution, and dried at 80° C. to obtain cobalt carbonate; the dried cobalt carbonate is calcined in a rotary kiln at a temperature of 680° C. for 5 hours to obtain cobalt tetroxide with a small particle size and narrow distribution.

[0055] The sample obtained in Example 1 was subjected to X-ray diffraction analysis (XRD). Figure 1 As shown, multiple sharp and high-intensity diffraction peaks are clearly presented. After comparison with a standard cobalt tetroxide XRD card, the characteristic peaks obtained are all cobalt tetroxide phases, and no other impurity phases are present. This shows that the cobalt tetroxide prepared by the method provided by the present invention is phase-pure and highly crystalline.

[0056] Figure 2 It can be seen that the particle size D50 of the cobalt trioxide prepared in this embodiment is 3.38 μm, the consistency is 0.216, the particle size is small and the distribution is narrow.

[0057] Example 2

[0058] This embodiment provides a method for preparing cobalt trioxide with small particle size and narrow distribution, comprising the following steps:

[0059] Step 1: Dissolve cobalt chloride hexahydrate and ammonium bicarbonate in water to obtain a first solution having a cobalt ion concentration of 110 g / L and a second solution having a bicarbonate ion concentration of 220 g / L; dissolve sodium lauryl sulfate in water to obtain a dispersant solution having a concentration of 0.15 mol / L;

[0060] Step 2: Using a reaction vessel with a double-layer stirring device, add 520L of water and 80L of ammonium bicarbonate solution as the base liquid into the reactor and heat it to 42°C;

[0061] Step 3: The first solution, the second solution, and the dispersant solution were added to the reaction vessel simultaneously. The flow rate of the cobalt solution was strictly controlled to be 350 L / h, and the flow rate of the dispersant solution was 50 L / h. The flow rate of the second solution was adjusted to control the pH value of the reaction system to be around 7.9. The reaction was carried out at a temperature of 42° C. and a rotation speed of 180 rpm for 25 hours to obtain a synthetic slurry.

[0062] Step 4: The synthetic slurry is washed and filtered with a 22 g / L ammonium bicarbonate solution, and dried at 80° C. to obtain cobalt carbonate; the dried cobalt carbonate is calcined in a rotary kiln at a temperature of 710° C. for 4 hours to obtain cobalt tetroxide with a small particle size and narrow distribution.

[0063] After testing, the particle size D50 of the cobalt tetroxide prepared in this embodiment is 3.296 μm, the consistency is 0.391, and the particle size is small and the distribution is narrow.

[0064] Example 3

[0065] This embodiment provides a method for preparing cobalt trioxide with small particle size and narrow distribution, comprising the following steps:

[0066] Step 1: Dissolve cobalt chloride hexahydrate and ammonium bicarbonate in water to obtain a first solution having a cobalt ion concentration of 120 g / L and a second solution having a bicarbonate ion concentration of 240 g / L; dissolve sodium lauryl sulfate in water to obtain a dispersant solution having a concentration of 0.2 mol / L;

[0067] Step 2: Using a reaction vessel with a double-layer stirring device, add 535L of water and 65L of ammonium bicarbonate solution as the base liquid into the reactor and heat it to 42°C;

[0068] Step 3: The first solution, the second solution, and the dispersant solution were simultaneously added to the reaction vessel. The flow rate of the cobalt solution was strictly controlled to 380 L / h, and the flow rate of the dispersant solution was 60 L / h. The flow rate of the second solution was adjusted to control the pH value of the reaction system to about 7.5. The reaction was carried out at a temperature of 42° C. and a rotation speed of 150 rpm for 30 hours to obtain a synthetic slurry.

[0069] Step 4: The synthetic slurry is washed and filtered with a 22 g / L ammonium bicarbonate solution, and dried at 80° C. to obtain cobalt carbonate; the dried cobalt carbonate is calcined in a rotary kiln at a temperature of 750° C. for 3 hours to obtain cobalt tetroxide with a small particle size and narrow distribution.

[0070] After testing, the particle size D50 of the cobalt tetroxide prepared in this embodiment is 3.373 μm, the consistency is 0.294, and the particle size is small and the distribution is narrow.

[0071] Example 4

[0072] This embodiment provides a method for preparing cobalt trioxide with small particle size and narrow distribution, comprising the following steps:

[0073] Step 1: Dissolve cobalt sulfate heptahydrate and sodium bicarbonate in water to obtain a first solution having a cobalt ion concentration of 140 g / L and a second solution having a bicarbonate ion concentration of 260 g / L; dissolve sodium lauryl sulfate in water to obtain a dispersant solution having a concentration of 0.1 mol / L;

[0074] Step 2: Using a reaction vessel with a double-layer stirring device, add 550L of water and 50L of ammonium bicarbonate solution as the base liquid into the reactor and heat it to 45°C;

[0075] Step 3: The first solution, the second solution, and the dispersant solution were added to the reaction vessel simultaneously. The flow rate of the cobalt solution was strictly controlled to be 320 L / h, and the flow rate of the dispersant solution was 55 L / h. The flow rate of the second solution was adjusted to control the pH value of the reaction system to be around 7.2. The reaction was carried out at a temperature of 45° C. and a rotation speed of 180 rpm for 30 hours to obtain a synthetic slurry.

[0076] Step 4: The synthetic slurry is washed and filtered with a 22 g / L ammonium bicarbonate solution, and dried at 80° C. to obtain cobalt carbonate; the dried cobalt carbonate is calcined in a rotary kiln at a temperature of 680° C. for 5 hours to obtain cobalt tetroxide with a small particle size and narrow distribution.

[0077] After testing, the particle size D50 of the cobalt tetroxide prepared in this embodiment is 3.538 μm, the consistency is 0.418, and the particle size is small and the distribution is narrow.

[0078] Comparative Example 1

[0079] This comparative example provides a method for preparing cobalt trioxide with small particle size, comprising the following steps:

[0080] Step 1: Dissolve a cobalt salt and a bicarbonate salt in water to obtain a first solution having a cobalt ion concentration of 130 g / L and a second solution having a bicarbonate ion concentration of 260 g / L;

[0081] Step 2: Using a reaction vessel with a double-layer stirring device, add 550L of water and 50L of ammonium bicarbonate solution as the base liquid into the reactor and heat it to 41°C;

[0082] Step 3: The first solution and the second solution were continuously added to the reactor in parallel, with the flow rate of the cobalt solution strictly controlled at 320 L / h and the pH value controlled at approximately 7.2. The reaction was carried out at a temperature of 41°C and a rotation speed of 220 rpm for 30 hours to obtain a synthetic slurry;

[0083] Step 4: The synthetic slurry is washed with 22 g / L ammonium bicarbonate solution, filtered, and dried at 80° C. to obtain cobalt carbonate; the dried cobalt carbonate is calcined in a rotary kiln at a calcination temperature of 680° C. for 5 hours to obtain cobalt tetroxide.

[0084] The main difference between this comparative example and the embodiment is that no dispersant solution was added during the reaction. Figure 3 From the particle size distribution results, it can be seen that under the conditions of the same reaction time, although the D50 of the cobalt trioxide prepared in this comparative example is relatively small, 2.804 μm, the particle size distribution is wide and the consistency is poor, with obvious front and back peaks, and the consistency is 1.263.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing cobalt trioxide, comprising the following steps:

[0087] Step 1: Dissolve a cobalt salt and a bicarbonate salt in water to obtain a first solution having a cobalt ion concentration of 130 g / L and a second solution having a bicarbonate ion concentration of 260 g / L; dissolve sodium lauryl sulfate in water to obtain a dispersant solution having a concentration of 0.1 mol / L;

[0088] Step 2: Using a reaction vessel with a double-layer stirring device, add 550L of water and 50L of ammonium bicarbonate solution as the base liquid into the reactor and heat it to 41°C;

[0089] Step 3: The first solution, the second solution, and the dispersant solution were added to the reaction vessel simultaneously. The flow rate of the cobalt solution was strictly controlled to 320 L / h, and the flow rate of the dispersant solution was 20 L / h. The flow rate of the second solution was adjusted to control the pH value of the reaction system to about 7.2. The reaction was carried out at a temperature of 41° C. and a rotation speed of 220 rpm for 30 hours to obtain a synthetic slurry.

[0090] Step 4: The synthetic slurry is washed with 22 g / L ammonium bicarbonate solution, filtered, and dried at 80° C. to obtain cobalt carbonate; the dried cobalt carbonate is calcined in a rotary kiln at a calcination temperature of 680° C. for 5 hours to obtain cobalt tetroxide.

[0091] The main difference between this comparative example and the example is that the flow rate of the dispersant solution in the reaction raw materials was adjusted from 55 L / h to 20 L / h. The cobalt trioxide prepared in this comparative example has a D50 of 5.012 μm, a D90 of 87.913 μm, and a consistency of 1.173, showing a bimodal state. This shows that in the preparation method of the present invention, controlling the flow rate ratio of the dispersant solution to the cobalt-containing solution within a reasonable range has an important influence on reducing the product particle size and improving the consistency of the particle size distribution.

[0092] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the present invention specification should be included in the protection scope of the present invention.

Claims

1. A method for preparing cobalt trioxide with small particle size and narrow distribution, characterized in that: The following steps are involved: S1. Dissolve a cobalt salt and a bicarbonate salt in water to obtain a first solution having a cobalt ion concentration of 110-140 g / L and a second solution having a bicarbonate ion concentration of 220-260 g / L; dissolve sodium lauryl sulfate in water to obtain a dispersant solution having a concentration of 0.1-0.2 mol / L; S2. Using a reaction vessel with a double-layer stirring device, add water and the second solution to submerge the bottom stirring device, and heat the reaction vessel to 40-45° C. under stirring; S3. Simultaneously adding the first solution, the second solution, and the dispersant solution into a reaction vessel, controlling the flow ratio of the first solution to the dispersant solution to be (32-38):(5-6), adjusting the flow rate of the second solution to control the pH value of the reaction system to be 7.0-7.9, and reacting at 40-45° C. for 25-30 hours to obtain a synthetic slurry; S4. Washing, filtering and drying the synthetic slurry to obtain cobalt carbonate; calcining the cobalt carbonate at high temperature to obtain cobalt trioxide with small particle size and narrow distribution.

2. The preparation method according to claim 1, characterized in that In step S1, the cobalt salt is selected from cobalt chloride and / or cobalt sulfate; and the bicarbonate is selected from ammonium bicarbonate and / or sodium bicarbonate.

3. The preparation method according to claim 1, characterized in that In step S2, the volume ratio of water to the second solution is (50-55):(5-8).

4. The preparation method according to claim 1, characterized in that In step S2, the stirring speed is 180-250 rpm.

5. The preparation method according to claim 1, characterized in that In step S3, the flow rate of the first solution is 320-380 L / h, and the flow rate of the dispersant solution is 50-60 L / h.

6. The preparation method according to claim 1, characterized in that In step S3, the feed mass ratio of the second solution to the first solution per unit time is (3-5):

1.

7. The preparation method according to claim 1, characterized in that In step S4, the solvent used for washing is ammonium bicarbonate solution, and the temperature for drying treatment is 80-100°C.

8. The preparation method according to claim 1, characterized in that The high temperature calcination treatment is performed at a temperature of 680-750° C. and for a time of 3-5 hours.

9. A cobalt trioxide with a small particle size and narrow distribution, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8; the particle size D50 of the small-particle-size narrow-distribution cobaltous oxide is 3.296-3.538 μm, and the consistency is 0.216-0.

418.

10. Use of the cobalt oxide with small particle size and narrow distribution according to claim 9 in a positive electrode material for lithium-ion batteries.

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