Preparation method of tricobalt tetroxide and application thereof

Abstract

This invention proposes a method for preparing cobalt tetroxide and its application, relating to the field of battery materials technology. The preparation method includes the following steps: S1: preparing a base solution with a pH of 7.5-9.0, heating it, adding a cobalt source and an alkali for a first-stage reaction to obtain a mixed slurry; S2: adding hydrogen peroxide to the mixed slurry for a second-stage reaction, adjusting the pH to 9.5-11 after addition, and aging to obtain a cobalt tetroxide slurry; in step S1, the Co in the cobalt source... 2+ With the OH provided by the base ‑ The molar ratio is (0.52~0.68):1; in step S2, the hydrogen peroxide reacts with the Co in the cobalt source. 2+ Molar ratio: n(H2O2):n(Co) 2+ The ratio of cobalt oxide to cobalt tetroxide is 0.3-0.38:1. This invention prepares cobalt tetroxide in one step using a wet co-precipitation method by precisely controlling reaction parameters. The resulting product has characteristics such as high purity cobalt tetroxide phase, high BET concentration, and good dispersibility.

Description

Technical Field

[0001] This invention relates to the field of battery materials technology, specifically to a method for preparing cobalt tetroxide and its application. Background Technology

[0002] The new energy vehicle industry is currently experiencing explosive growth, and the most crucial technology determining its success is the lithium-ion battery. Currently, commercially available new energy vehicle batteries primarily use ternary lithium-ion batteries, lithium iron phosphate batteries, sodium-ion batteries, and a very small number of lithium manganese oxide batteries, with the first two types of cathode materials dominating the market. The market is increasingly demanding higher performance from lithium-ion batteries, including safety, energy density, and battery cycle performance.

[0003] To improve energy density, the development of ternary cathode materials tends towards higher nickel content. However, excessively high nickel content can compromise battery safety. Furthermore, the stability of the ternary cathode material structure deteriorates under high voltage and at high rates, exacerbating cation mixing.

[0004] To address the aforementioned technical challenges, modification methods such as coating are commonly used to alter ternary cathode materials. The most common approach is to use micron-sized, sheet-like cobalt hydroxide particles for surface treatment to improve performance. However, this method cannot meet the demands of higher-end battery performance, thus necessitating the development of a novel modification material. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a method for preparing cobalt tetroxide and its application, wherein nano-sized cobalt tetroxide can be directly obtained by a one-step wet co-precipitation method.

[0006] According to a first aspect of the present invention, a method for preparing cobalt tetroxide is provided, comprising the following steps: S1: Prepare a base solution with a pH of 7.5~9.0, heat it up, add a cobalt source and alkali to carry out a reaction, and obtain a mixed slurry; S2: Add hydrogen peroxide to the mixed slurry for a two-stage reaction. After the addition is complete, adjust the pH to 9.5~11 and age it to obtain cobalt tetroxide slurry. After solid-liquid separation, cobalt tetroxide is obtained. In step S1, the Co in the cobalt source 2+ With the OH provided by the base - molar ratio n(Co) 2+ ):n(OH - )=(0.52~0.68):1; In step S2, the hydrogen peroxide reacts with the Co in the cobalt source. 2+ The molar ratio of n(H2O2):n(Co)2+ =(0.3~0.38):1.

[0007] In some embodiments, the pH of the substrate solution is 8.1 to 8.7.

[0008] The preparation method proposed in this invention mainly consists of three stages. Stage 1: The cobalt source and alkali react at a lower pH and lower temperature for a shorter time. Under these reaction conditions, a mixed slurry containing α-Co(OH)₂ and β-Co(OH)₂ is obtained. The process is further refined by controlling the Co content... 2+ and OH - The molar ratio and pH are controlled within a specific range to carry out the following reaction equations ① and ②, thereby obtaining a mixed slurry containing α-Co(OH)2 and β-Co(OH)2 with specific compositions.

[0009] ① Co 2+ + 2OH - → α-Co(OH)2; ② Co 2+ + 2OH - → β-Co(OH)2.

[0010] If the pH of the system is too low, the content of α-Co(OH)2 in the mixed slurry will increase significantly, while if the pH of the system is too high, the content of Co... 2+ It tends to form β-Co(OH)2. Therefore, by adjusting the pH within a specific range, the relative contents of α-Co(OH)2 and β-Co(OH)2 in the mixed slurry can be controlled within a suitable range, thereby increasing the Co content. 2+ Conversion rate to Co3O4.

[0011] The theoretical mass content of Co in β-Co(OH)₂ is 63.41%, while the crystal structure of α-Co(OH)₂ is similar to that of hydrotalcite and can be represented as Co. 1+0.5x (OH)2(Cl) x (H2O) n Where 0 < x ≤ 0.5, and Cl can be other intercalating ions, such as SO42-. 2- NO3 - It can be seen that the Co mass content in α-Co(OH)2 is lower than that in β-Co(OH)2, meaning that the Co mass content of the two phases has a certain difference. Therefore, the Co mass content in the mixed phase can reflect the relative content of the two phases, α-Co(OH)2 and β-Co(OH)2.

[0012] Specifically, in the solid phase of the mixed slurry in step S1, the content of Co element is 54.57% to 55.19%.

[0013] Stage 2 - Oxidation: A specific amount of hydrogen peroxide is added, and the reaction time is controlled to regulate the progress of reaction equations ③ and ④ below. All the corresponding cobalt hydroxide is converted to cobalt tetroxide. Within a relatively low pH range, the reduction potential of α-Co(OH)₂ is more positive than that of β-Co(OH)₂, making it less susceptible to oxidation. Co(OH)₃, being hexagonal, is a predominantly unstable intermediate product that readily reacts with the +2 valence, hexagonal α-Co(OH)₂ to transform into the cubic Co₃O₄.

[0014] ③2[β-Co(OH)2] + H2O2→ 2Co(OH)3; ④ x α-Co(OH)2+ yCo(OH)3+ zH2O2→ mCo3O4+ nH2O.

[0015] If too much β-Co(OH)2 is generated, the resulting Co(OH)3 is unstable and dehydrates directly to form stable cobalt hydroxyoxide, with the reaction formula Co(OH)3 → CoOOH + 2H2O.

[0016] Stage 3 - Aging: The pH of the slurry in the reactor is increased, and the residual H2O2 in the reactor further reacts with the remaining Co. 2+ The reaction can improve the purity of the cobalt tetroxide phase in the reactor. This process is mainly carried out according to reaction equations ②③④.

[0017] In some embodiments, the base liquid is a sodium hydroxide solution.

[0018] In some embodiments, the cobalt source is selected from at least one of cobalt chloride, cobalt sulfate, or cobalt nitrate.

[0019] In some embodiments, the base is selected from sodium hydroxide.

[0020] In some embodiments, in step S1, the temperature of the first stage of reaction is 35~45°C, and the reaction time is 10~20 min.

[0021] In some implementations, the reaction time in step S1 is 30-40 minutes.

[0022] In some embodiments, the aging time is 50 to 80 minutes.

[0023] In some embodiments, the preparation method further includes: sequentially washing, drying, and grinding the cobalt tetroxide; the washing uses wash water containing a softening agent; the softening agent is selected from at least one of ethanol, isopropanol, or acetone, and the mass percentage of the softening agent in the wash water is 0.1 wt% to 1 wt%. The softening agent is a water-soluble organic solvent that can be adsorbed onto the surface of nano-cobalt tetroxide particles, reducing the hydrogen bonding and other forces between particles, thereby mitigating the agglomeration of the material during the drying process.

[0024] In some embodiments, the drying temperature is 60~80°C.

[0025] In some embodiments, the dry atmosphere is a mixture of nitrogen and oxygen, wherein the oxygen volume content is 0.1% to 1%.

[0026] In some embodiments, the drying atmosphere is a nitrogen atmosphere.

[0027] In some embodiments, the drying time is 8 to 10 hours.

[0028] Because the washing water contains a small amount of softener (soluble organic matter), the drying temperature can be appropriately reduced to 60~80℃ compared to the conventional method.

[0029] In some embodiments, the grinding is an air jet mill.

[0030] According to a second aspect of the present invention, a cobalt tetroxide is provided, which is prepared by the preparation method described in the first aspect of the present invention, wherein the cobalt tetroxide has a particle size of 0.05~1μm.

[0031] According to a third aspect of the present invention, the application of cobalt tetroxide prepared by the preparation method described in the first aspect of the present invention or cobalt tetroxide described in the second aspect of the present invention in the cathode material of lithium-ion batteries is proposed.

[0032] According to one embodiment of the present invention, at least the following beneficial effects are achieved: 1. Common methods for preparing cobalt tetroxide are all two-step processes: wet synthesis of intermediates such as cobalt hydroxide / cobalt carbonate / cobalt hydroxyl, followed by dry calcination to obtain cobalt tetroxide. This invention, through precise control of reaction parameters, employs a one-step wet co-precipitation method to synthesize cobalt tetroxide. The resulting particles have a sand-like morphology and exhibit high purity, high BET concentration, and good dispersibility.

[0033] 2. When washing, use a softener to reduce the strong polar forces such as hydrogen bonds between particles and prevent them from agglomerating. At the same time, high-purity and well-dispersible nano-cobalt tetroxide products can be prepared simply by using conventional pulverizing equipment. Attached Figure Description

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a SEM image of the cobalt tetroxide sample obtained in Example 1 of the present invention; Figure 2 This is a SEM image of the cobalt tetroxide sample obtained in Example 2 of the present invention; Figure 3 This is a SEM image of the cobalt tetroxide sample prepared in Comparative Example 1 of this invention. Figure 4 This is a SEM image of the cobalt tetroxide sample prepared in Comparative Example 2 of this invention. Figure 5 This is a SEM image of the cobalt tetroxide sample prepared in Comparative Example 3 of this invention. Figure 6 This is a SEM image of the cobalt tetroxide sample prepared in Comparative Example 4 of this invention. Figure 7 The image shows the XRD pattern of the cobalt tetroxide sample prepared in Example 1 of this invention. Figure 8 The image shows the XRD pattern of the process sample obtained in the first stage of synthesis in Example 1 of this invention. Figure 9 The image shows the XRD pattern of the cobalt tetroxide sample obtained in Example 2 of this invention. Figure 10 The image shows the XRD pattern of the process sample obtained in the first stage of synthesis in Example 2 of this invention. Figure 11 The image shows the XRD pattern of the cobalt tetroxide sample prepared in Comparative Example 1 of this invention. Figure 12 The image shows the XRD pattern of the cobalt tetroxide sample prepared in Comparative Example 2 of this invention. Figure 13 The image shown is the XRD pattern of the cobalt tetroxide sample prepared in Comparative Example 3 of this invention. Figure 14 The image shown is the XRD pattern of the cobalt tetroxide sample prepared in Comparative Example 4 of this invention. Figure 15 This is a particle size distribution curve of the cobalt tetroxide sample prepared in Example 1 of the present invention. Figure 16 This is a particle size distribution curve of the cobalt tetroxide sample obtained in Example 2 of the present invention. Figure 17 This is a particle size distribution curve of the cobalt tetroxide sample prepared in Comparative Example 1 of this invention. Figure 18 This is a particle size distribution curve of the cobalt tetroxide sample prepared in Comparative Example 2 of this invention. Figure 19 This is a particle size distribution curve of the cobalt tetroxide sample prepared in Comparative Example 3 of this invention. Figure 20 This is a particle size distribution curve of the cobalt tetroxide sample prepared in Comparative Example 4 of this invention. Detailed Implementation

[0035] The following will describe the concept and technical effects of the present invention clearly and completely with reference to the embodiments, so as to fully understand the purpose, features and effects of the present invention, but the present invention is not limited to the scope of the embodiments described.

[0036] Unless otherwise specified, the experimental methods in the following examples were performed according to conventional methods and conditions. Unless otherwise specified, the raw materials, reagents or apparatus used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0037] Example 1 This embodiment provides a method for preparing nano-cobalt tetroxide, including the following steps: (1) Add an appropriate amount of pure water to a 100L reactor and adjust the pH of the bottom solution to 8.1 with sodium hydroxide solution; (2) After the base solution is prepared, the synthesis reaction is divided into 3 stages. Stage 1: The temperature inside the reactor is controlled at 40~45℃, and cobalt chloride solution and sodium hydroxide solution are pumped in simultaneously under stirring at 400rpm. The cobalt chloride solution contains Co 2+ The ion pumping rate is 15.6 kg / h, the NaOH pumping rate in the liquid alkali is 19.25 kg / h, and the Co... 2+ The molar ratio of H₂O₂ to total Co is 0.55:1, and the reaction time is 15 min. Second stage: Immediately after the first stage, add 2.55 kg of hydrogen peroxide (30 wt%), and control the reaction time at 30 min. The molar ratio of hydrogen peroxide to total Co is controlled at n(H₂O₂):n(Co). 2+ =0.34:1. Stage 3: After the end of Stage 2, add liquid alkali to adjust the pH of the slurry in the reactor to 9.65, then age for 60 minutes to complete the entire synthesis reaction.

[0038] (3) After filtration, the synthesized slurry is treated with 1m solution containing 0.3wt% softener ethanol. 3 The material is washed at 60±5℃ to remove impurities. It is then dried in a nitrogen-filled oven at a low temperature of 60-80℃, with the oxygen content controlled at 0.5%~1%, for 9 hours. The dried material is then pulverized using an air jet mill to obtain well-dispersible nano-cobalt tetroxide.

[0039] Example 2 This embodiment provides a method for preparing nano-cobalt tetroxide, including the following steps: (1) Add an appropriate amount of pure water to a 100L reactor and adjust the pH of the bottom solution to 8.7 with sodium hydroxide solution; (2) After the base solution is prepared, the synthesis reaction is divided into 3 stages. Stage 1: The temperature inside the reactor is controlled at 35~40℃, and cobalt chloride solution and sodium hydroxide solution are pumped in simultaneously under suitable stirring conditions. The cobalt chloride solution contains Co 2+ The ion pumping rate is 15.6 kg / h, the NaOH pumping rate in the liquid alkali is 16.29 kg / h, and the Co... 2+ The molar ratio of H₂O₂ to total Co is 0.65:1, and the reaction time is 16 min. Second stage: Immediately after the first stage, add 2.7 kg of hydrogen peroxide (30 wt%), and control the reaction time at 35 min. The molar ratio of hydrogen peroxide to total Co is controlled at n(H₂O₂):n(Co). 2+ =0.36:1. Stage 3: After the end of Stage 2, add liquid alkali to adjust the pH of the slurry in the reactor to 10.8, then age for 60 minutes. The entire synthesis reaction is then complete.

[0040] (3) After filtration, the synthesized slurry is treated with 1m solution containing 0.8wt% isopropanol as a softener. 3 The material is washed at 60±5℃ to remove impurities. It is then dried in a nitrogen-filled oven at a low temperature of 60-80℃, with the oxygen content controlled at 0.5%~1%, for 8 hours. The dried material is then pulverized using an air jet mill to obtain well-dispersible nano-cobalt tetroxide.

[0041] Comparative Example 1 This comparative example provides a method for preparing nano-cobalt tetroxide, comprising the following steps: (1) Add an appropriate amount of pure water to a 100L reactor and adjust the pH of the bottom solution to 7.2 with sodium hydroxide solution; (2) After the base solution is prepared, the synthesis reaction is divided into 3 stages. Stage 1: The temperature inside the reactor is controlled at 40-45℃, and cobalt chloride solution and sodium hydroxide solution are pumped in simultaneously under suitable stirring conditions. The cobalt chloride solution contains Co 2+ The ion pumping rate is 15.6 kg / h, the NaOH pumping rate in the liquid alkali is 14.12 kg / h, and the Co... 2+ The molar ratio of H₂O₂ to total Co is 0.75:1, and the reaction time is 11 min. Second stage: Immediately after the first stage, add 2.55 kg of hydrogen peroxide (30 wt%), and control the reaction time at 30 min. The molar ratio of hydrogen peroxide to total Co is controlled at n(H₂O₂):n(Co). 2+=0.34:1. Stage 3: After the end of Stage 2, add liquid alkali to adjust the pH of the slurry in the reactor to 9.65, and then age for 60 minutes to complete the entire synthesis reaction.

[0042] (3) After filtration, the synthesized slurry is treated with 1m solution containing 0.6wt% acetone softener. 3 The material is washed at 60±5℃ to remove impurities. It is then dried in a nitrogen-filled oven at a low temperature of 60~80℃, with the oxygen content controlled at 0.5%~1%, for 9 hours. The dried material is then pulverized using an air jet mill to obtain the finished nano-cobalt tetroxide.

[0043] Comparative Example 2 This comparative example provides a method for preparing nano-cobalt tetroxide, comprising the following steps: (1) Add an appropriate amount of pure water to a 100L reactor and adjust the pH of the bottom solution to 10.7 with sodium hydroxide solution; (2) After the base solution is prepared, the synthesis reaction is divided into 3 stages. Stage 1: The temperature inside the reactor is controlled at 40-45℃, and cobalt chloride solution and sodium hydroxide solution are pumped in simultaneously under suitable stirring conditions. The cobalt chloride solution contains Co 2+ The ion pumping rate is 15.6 kg / h, the NaOH pumping rate in the liquid alkali is 23.53 kg / h, and the Co... 2+ The molar ratio of H₂O₂ to total Co is 0.45:1, and the reaction time is 13 min. Second stage: Immediately after the first stage, add 2.55 kg of hydrogen peroxide (30 wt%), and control the reaction time at 30 min. The molar ratio of hydrogen peroxide to total Co is controlled at n(H₂O₂):n(Co). 2+ =0.34:1. Stage 3: After the end of Stage 2, add liquid alkali to adjust the pH of the slurry in the reactor to 10.9, and then age for 60 minutes to complete the entire synthesis reaction.

[0044] (3) After filtration, the synthesized slurry is treated with 1m solution containing 0.2wt% acetone as a softener. 3 The material is washed at 60±5℃ to remove impurities. It is then dried in a nitrogen-filled oven at a low temperature of 60~80℃, with the oxygen content controlled at 0.5%~1%, for 9 hours. The dried material is then pulverized using an air jet mill to obtain well-dispersible nano-cobalt tetroxide.

[0045] Comparative Example 3 This comparative example provides a method for preparing nano-cobalt tetroxide, including the following steps: (1) Add an appropriate amount of pure water to a 100L reactor and adjust the pH of the bottom solution to 8.7 with sodium hydroxide solution; (2) After the base solution is prepared, the synthesis reaction is divided into 3 stages. Stage 1: The temperature inside the reactor is controlled at 35~40℃, and cobalt chloride solution and sodium hydroxide solution are pumped in simultaneously under suitable stirring conditions. The cobalt chloride solution contains Co 2+ The ion pumping rate is 15.6 kg / h, the NaOH pumping rate in the liquid alkali is 16.29 kg / h, and the Co... 2+ The molar ratio of H₂O₂ to total Co is 0.65:1, and the reaction time is 16 min. Second stage: Immediately after the first stage, add 1.5 kg of hydrogen peroxide (30 wt%), and control the reaction time at 35 min. The molar ratio of hydrogen peroxide to total Co is controlled at n(H₂O₂):n(Co). 2+ =0.2:1. Stage 3: After the end of Stage 2, add liquid alkali to adjust the pH of the slurry in the reactor to 10.8, then age for 60 minutes. The entire synthesis reaction is then complete.

[0046] (3) After filtration, the synthesized slurry is washed with 1 m³ of washing water at 60±5℃ containing 0.8wt% isopropanol (a softener) to remove impurities. Then, it is dried in a nitrogen-filled oven at 60-80℃ for 8 hours, with the oxygen content controlled at 0.5%~1%. The dried material is then pulverized by an air jet mill to obtain a well-dispersible nano-cobalt tetroxide product.

[0047] Comparative Example 4 This comparative example provides a method for preparing nano-cobalt tetroxide, including the following steps: (1) Add an appropriate amount of pure water to a 100L reactor and adjust the pH of the bottom solution to 8.7 with sodium hydroxide solution; (2) After the base solution is prepared, the synthesis reaction is divided into 3 stages. Stage 1: The temperature inside the reactor is controlled at 35~40℃, and cobalt chloride solution and sodium hydroxide solution are pumped in simultaneously under suitable stirring conditions. The cobalt chloride solution contains Co 2+ The ion pumping rate is 15.6 kg / h, the NaOH pumping rate in the liquid alkali is 16.29 kg / h, and the Co... 2+ The molar ratio of H₂O₂ to total Co is 0.65:1, and the reaction time is 16 min. Second stage: Immediately after the first stage, add 3.75 kg of hydrogen peroxide (30 wt%), and control the reaction time at 35 min. The molar ratio of hydrogen peroxide to total Co is controlled at n(H₂O₂):n(Co). 2+ =0.5:1. Stage 3: After the end of Stage 2, add liquid alkali to adjust the pH of the slurry in the reactor to 10.8, then age for 60 minutes. The entire synthesis reaction is then complete.

[0048] (3) After filtration, the synthesized slurry is treated with 1m solution containing 0.8wt% isopropanol as a softener.3 The material is washed with water at 60±5℃ to remove impurities. Then it is dried in a nitrogen-filled oven at a low temperature of 60-80℃, with the oxygen content controlled at 0.5%~1%, for 8 hours. The dried material is then pulverized using an air jet mill to obtain well-dispersible nano-cobalt tetroxide.

[0049] Test case The cobalt tetroxide prepared in Examples 1-2 and Comparative Examples 1-4 was tested, and the results are shown in Table 1 below. The main content (Co mass content) was determined using a potentiometric titrator, BET was measured using a fully automated rapid surface area analyzer, particle size was measured using a Malvern 3000 laser particle size analyzer, and impurities Na and Cl were measured using inductively coupled plasma atomic emission spectrometry.

[0050] Table 1. Test data of cobalt tetroxide samples

[0051] The Co content of the intermediate products generated in the first stage of the reaction process of Examples 1-2 and Comparative Examples 1-4 was tested, and the results are shown in Table 2 below.

[0052] Table 2 Test data of the final sample at the end of reaction stage 1

[0053] As can be seen from the table above, in Comparative Example 1, the amount of NaOH pumped in during the first stage of the synthesis reaction was relatively low, and the amount of Co... 2+ Failed to fully react, and Co 2+ Compared to Example 1, the reaction products showed a higher proportion of α-Co(OH)2 and a lower proportion of β-Co(OH)2, resulting in a lower Co content than the preferred range (54.57%~55.19%), thus leading to a decrease in the Co3O4 yield. Figure 11 A distinct characteristic peak of α-Co(OH)₂ can be observed. Since the crystal structure of α-Co(OH)₂ is similar to that of hydrotalcite (layered bimetallic hydroxide, LDH), the structural characteristics of LDH are: ① the main layers consist of two metal ions with different valence states (e.g., Mg²⁺ ... 2+ And Al 3+ Co 2+ And Al 3+ ) and hydroxide ions (OH) - ) together form a positively charged layer; ② interlayer anions (e.g., CO32-) 2- Cl - ) Neutralizes the positive charge between the main layers; ③ To fill the space, water molecules will also coexist; therefore, the standard XRD card 51-0045# Co6Al2CO3(OH) 16 ·4H2O and 89-0461#Mg 0.833Al 0.167 (OH)2(CO3) 0.083 0.75H2O can represent the crystal structure of α-Co(OH)2. 02-0925, 74-1057, and 30-0443 are standard cards for β-Co(OH)2.

[0054] In Comparative Example 2, the NaOH pumping rate was too high in the first stage of the synthesis reaction, and the Co... 2+ Compared to Example 1, the reaction product showed a higher proportion of β-Co(OH)2 and a lower proportion of α-Co(OH)2, resulting in a higher Co mass content than the preferred range and a decreased Co3O4 yield. Figure 12 It can be seen that CoOOH is present in the product, which is formed by the dehydration and transformation of residual Co(OH)3.

[0055] In Comparative Example 3, the amount of hydrogen peroxide added in the second stage of the synthesis reaction was too low, failing to completely oxidize β-Co(OH)2, resulting in a decrease in the yield of Co3O4. Figure 13 It can be seen that the product clearly contains β-Co(OH)2.

[0056] In Comparative Example 4, the amount of hydrogen peroxide added in the second stage of the synthesis reaction was too high, resulting in the formation of more CoOOH. The overall reaction formula is as follows: ,Depend on Figure 14 It can also be seen that the sample clearly contains CoOOH.

[0057] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing cobalt tetroxide, characterized in that, Includes the following steps: S1: Prepare a base solution with a pH of 7.5~9.0, heat it up, add a cobalt source and alkali to carry out a reaction, and obtain a mixed slurry; S2: Add hydrogen peroxide to the mixed slurry for a two-stage reaction. After the addition is complete, adjust the pH to 9.5~11 and age it to obtain cobalt tetroxide slurry. After solid-liquid separation, cobalt tetroxide is obtained. In step S1, the Co in the cobalt source 2+ With the OH provided by the base - molar ratio n(Co) 2+ ):n(OH - ) = (0.52~0.68):1; In step S2, the hydrogen peroxide reacts with the Co in the cobalt source. 2+ The molar ratio of n(H2O2):n(Co) 2+ =(0.3~0.38):

1.

2. The preparation method according to claim 1, characterized in that, In step S1, the pH of the base solution is 8.1 to 8.

7.

3. The preparation method according to claim 1, characterized in that, The base liquid is a sodium hydroxide solution.

4. The preparation method according to claim 1, characterized in that, The cobalt source is selected from at least one of cobalt chloride, cobalt sulfate, or cobalt nitrate; and / or, the base is selected from sodium hydroxide.

5. The preparation method according to claim 1, characterized in that, In step S1, the temperature of the first stage of reaction is 35~45℃, and the reaction time is 10~20min; And / or, the time for the two-stage reaction is 30-40 minutes.

6. The preparation method according to claim 1, characterized in that, In step S2, the aging time is 50-80 minutes.

7. The preparation method according to claim 1, characterized in that, Also includes: The cobalt tetroxide is sequentially washed, dried, and ground; the washing is done with wash water containing a softening agent; the softening agent is selected from at least one of ethanol, isopropanol, or acetone, and the mass percentage of the softening agent in the wash water is 0.1wt% to 1wt%.

8. The preparation method according to claim 7, characterized in that, The drying temperature is 60~80℃; and / or the drying atmosphere is a mixture of nitrogen and oxygen, wherein the oxygen volume content is 0.1%~1%; and / or the drying time is 8~10h.

9. A cobalt tetroxide, prepared by the preparation method according to any one of claims 1-8, characterized in that, The particle size is 0.05~1μm.

10. The application of cobalt tetroxide prepared by the preparation method according to any one of claims 1-8 or cobalt tetroxide according to claim 9 in the cathode material of lithium-ion batteries.

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