Nano cobaltosic oxide as well as preparation method and application thereof

Abstract

The invention provides nano cobaltosic oxide as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing a cobalt salt solution and a precipitant solution, and carrying out a co-precipitation reaction to obtain a cobalt carbonate intermediate material; and (2) mixing the cobalt carbonate intermediate material and a crystal growth inhibitor, and sintering to obtain the nano cobaltosic oxide. According to the preparation method provided by the invention, the nanometer cobaltosic oxide material can be continuously produced, and the particle size pitch of the nanometer cobaltosic oxide material is narrower and the dispersity is good.

Description

Technical Field

[0001] The invention belongs to the technical field of nanomaterials and relates to nano cobalt tetroxide and a preparation method and application thereof. Background Art

[0002] With the rapid development of new energy, catalysis, and electronic devices, nano-cobalt tetroxide (Co3O4) has become a research hotspot due to its unique physicochemical properties (such as high theoretical specific capacity, excellent catalytic activity, and magnetism). As an important transition metal oxide, cobalt tetroxide (Co3O4) has shown significant advantages in lithium-ion battery anode materials, supercapacitors, gas sensors, and catalytic oxidation reactions. However, Co3O4 prepared by traditional methods often faces problems such as uneven particle size and severe agglomeration, which limits its performance. In view of the above problems, the development of controllable synthesis technology of nano-Co3O4 has become a key research direction. In recent years, preparation strategies such as sol-gel method, hydrothermal method, and template method have been widely explored, aiming to prepare nano-cobalt tetroxide with small particle size and few lattice defects to optimize electrochemical and catalytic performance. In addition, green synthesis and low-cost large-scale preparation are also the focus of current research to meet the needs of industrial applications.

[0003] Therefore, how to obtain nano-cobalt tetroxide materials with uniform particle size and good dispersibility is a technical problem that needs to be solved urgently. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a nano-cobalt oxide and its preparation method and use. The preparation method provided by the present invention can continuously produce nano-cobalt oxide material with a narrower particle size and good dispersibility.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing nano-cobalt tetroxide, the preparation method comprising the following steps:

[0007] (1) mixing a cobalt salt solution and a precipitant solution, and performing a coprecipitation reaction to obtain a cobalt carbonate intermediate material;

[0008] (2) Mixing a cobalt carbonate intermediate material and a crystal growth inhibitor, and sintering to obtain the nano-cobalt tetroxide.

[0009] The present invention first prepares a cobalt carbonate intermediate material with finer primary grains through a coprecipitation method, and then adds a grain growth inhibitor for calcination, thereby preventing the grains from fusing with each other during the calcination process, fusing small grains into large particles, and avoiding particle agglomeration, thereby preparing nano-scale cobalt trioxide with smaller particle size, more uniform distribution and narrower diameter distance; and can realize continuous production; the preparation process is simple and easy to operate, and is suitable for large-scale production.

[0010] In the present invention, if a grain growth inhibitor is not added, problems such as grain fusion and adhesion and large-scale particle agglomeration will occur during the calcination process, thereby failing to obtain a nano-cobalt tetroxide material with a small particle size and narrow diameter distance.

[0011] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0012] Preferably, the concentration of cobalt ions in the cobalt salt solution in step (1) is 80 g / L to 160 g / L, for example, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L or 160 g / L, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0013] Preferably, the concentration of the precipitant solution in step (1) is 210 g / L to 260 g / L, for example, 210 g / L, 220 g / L, 230 g / L, 240 g / L, 250 g / L or 260 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] Preferably, in step (2), the feed flow ratio of the cobalt salt solution and the precipitant solution is 1:(0.1-3), for example, 1:0.1, 1:0.3, 1:0.5, 1:0.8, 1:1, 1:1.3, 1:1.5, 1:1.8, 1:2, 1:2.3, 1:2.5, 1:2.8 or 1:3, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0015] The present invention has found that by regulating the feed flow rate ratio of the cobalt salt solution and the precipitant solution to 1: (0.1-3), the particle size of the cobalt carbonate intermediate material can be effectively regulated, and a cobalt carbonate intermediate material with finer primary grains can be obtained.

[0016] It should be noted that the cobalt salt in the present invention includes but is not limited to at least one of cobalt nitrate, cobalt chloride, cobalt acetate or cobalt sulfate; the precipitant includes but is not limited to at least one of ammonium carbonate, ammonium bicarbonate, sodium bicarbonate or sodium carbonate.

[0017] Preferably, the mixed raw materials in step (1) also include a dopant solution.

[0018] It is understandable that the present invention can be used to dope products according to different target requirements.

[0019] For example, doping can be performed directly in the bulk phase of the cobalt carbonate intermediate material. In addition, the dopant solution can be added in parallel with the cobalt salt solution and the precipitant solution, or it can be first mixed with the cobalt salt to obtain a mixed solution of the cobalt salt and the dopant, and then co-precipitated with the precipitant solution. The specific addition method can be adaptively selected and adjusted by those skilled in the art according to conventional technical solutions. Further, the dopant includes at least one of aluminum salt, magnesium salt, zirconium salt or titanium salt.

[0020] Preferably, the reaction temperature of the coprecipitation reaction in step (1) is 35°C to 70°C, for example, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C or 70°C, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the pH value of the coprecipitation reaction in step (1) is 7 to 9, for example, 7, 7.3, 7.5, 7.8, 8, 8.3, 8.5, 8.8 or 9, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] Preferably, the rotation speed of the coprecipitation reaction in step (1) is 100 r / min to 450 r / min, for example, 100 r / min, 130 r / min, 150 r / min, 180 r / min, 200 r / min, 230 r / min, 250 r / min, 280 r / min, 300 r / min, 330 r / min, 350 r / min, 380 r / min, 400 r / min, 430 r / min or 450 r / min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, after the coprecipitation reaction in step (1) is completed, aging, washing and drying are carried out in sequence.

[0024] Preferably, the median particle size D50 of the cobalt carbonate intermediate material in step (1) is ≥100 nm, preferably 100 nm to 1 μm, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0025] The coprecipitation reaction provided by the present invention can obtain a cobalt carbonate intermediate material with a relatively small median particle size. The present invention further preferably uses a cobalt carbonate intermediate material with a D50 of 100 nm to 1 μm, which is more conducive to controlling subsequent calcination. Too large a particle size will lead to reduced contact between the grain growth inhibitor and the particles, thereby failing to exert its effect. Moreover, too large a particle size will make it more difficult to disperse during subsequent calcination.

[0026] Preferably, the mass ratio of the cobalt carbonate intermediate material to the crystal growth inhibitor in step (2) is 1:(0.001-0.01), for example, 1:0.001, 1:0.002, 1:0.003, 1:0.004, 1:0.005, 1:0.006, 1:0.007, 1:0.008, 1:0.009 or 1:0.01, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0027] For the technical solution of the present invention, the mass ratio of the cobalt carbonate intermediate material to the crystal growth inhibitor in step (2) is 1:(0.001-0.01), which can better play the role of the grain growth inhibitor, thereby obtaining nanoparticles with smaller diameters.

[0028] Preferably, the crystal growth inhibitor in step (2) includes any one of VC, Cr3C2 or Nb2O5, or a combination of at least two of them.

[0029] Preferably, the heating rate of the sintering in step (2) is 5°C / min to 20°C / min, for example, 5°C / min, 8°C / min, 10°C / min, 13°C / min, 15°C / min, 18°C / min or 20°C / min, etc., but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0030] Preferably, the holding temperature of the sintering in step (2) is 450°C to 700°C, for example, 450°C, 500°C, 550°C, 600°C, 650°C or 700°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0031] Preferably, the holding time for sintering in step (2) is 30 min to 120 min, for example, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0032] Preferably, the sintering in step (2) is carried out in an oxygen-containing atmosphere.

[0033] Preferably, the sintering method in step (2) includes dynamic sintering.

[0034] It is understandable that the dynamic sintering described in the present invention is relative to the static sintering, that is, the material is in a non-static state during sintering, such as rotary kiln sintering, fluidized bed sintering or vibration sintering.

[0035] In the present invention, the dynamic sintering method is selected to further ensure that the agglomerated particles are better dispersed during the calcination process, thereby more effectively playing the role of a crystal growth inhibitor, inhibiting the mutual fusion between grains, and obtaining a nano-cobalt tetroxide material with smaller particle size, more uniform distribution and narrower diameter distance.

[0036] Preferably, the median particle size D50 of the nano-cobalt tetroxide in step (2) is 200 nm to 600 nm, for example, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm or 600 nm, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0037] In a second aspect, the present invention provides a nano-cobalt tetroxide, which is prepared by the preparation method described in the first aspect.

[0038] The nanometer cobalt trioxide of the present invention has the advantages of small particle size, uniform distribution and narrow diameter distance, which is more conducive to its performance in various fields.

[0039] In a third aspect, the present invention further provides a use of nano-cobalt tetroxide, which includes using the nano-cobalt tetroxide described in the second aspect in any one or at least two of the fields of new energy, catalysis, or electronic devices.

[0040] The nano-cobalt tetroxide of the present invention has multiple uses, and those skilled in the art can select and adjust it according to actual needs.

[0041] For example, when it is used in the field of new energy, it can be used as a precursor of lithium cobalt oxide positive electrode materials. When used as a lithium cobalt oxide precursor, dopants can be doped during the preparation process.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention first prepares a cobalt carbonate intermediate material with finer primary grains through a coprecipitation method, and then adds a grain growth inhibitor for calcination, thereby preventing the grains from fusing with each other during the calcination process, fusing small grains into large particles, and avoiding particle agglomeration, thereby preparing nano-scale cobalt trioxide with smaller particle size, more uniform distribution and narrower diameter distance; and can realize continuous production; the preparation process is simple and easy to operate, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the SEM image of nano-cobalt tetroxide provided in Example 1. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions.

[0047] In the description of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly indicate the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0048] Example 1

[0049] This embodiment provides a method for preparing nano-cobalt tetroxide, and the preparation method is as follows:

[0050] S1: First, prepare cobalt chloride salt into solution A with a Co concentration of 120g / L, and prepare 230g / L ammonium carbonate solution B;

[0051] S2: Pure water and solution B are added as the reaction base liquid, and the feed flow rate of solution A and solution B is simultaneously introduced into the reactor at a ratio of 1:0.1 to carry out a coprecipitation reaction. During the reaction, the feed amount of solution A and solution B is adjusted to ensure the pH value of the process is stable. The reaction temperature is controlled at 50°C, the pH is controlled at 7.8, and the rotation speed is 450r / min. When the reaction reaches a median particle size D50 of 550nm, the reactor is stopped to obtain a reaction slurry after the coprecipitation reaction;

[0052] S3: The reaction slurry is transferred to an aging tank and aged at 60° C. The aged material is washed with hot water at 80° C. and then dried at 100° C. to obtain a cobalt carbonate intermediate material with a median particle size D50 of 550 nm;

[0053] S4: The cobalt carbonate intermediate material and the grain growth inhibitor VC are added to a mixer at a mass ratio of 1:0.005 and mixed evenly. In a mixed gas environment of nitrogen and air, the temperature is raised to 600° C. at a heating rate of 10° C. / min and the mixed material is calcined in a rotary kiln. The calcination stage is kept warm for 60 minutes, and the heating is stopped to obtain the nano-cobalt tetroxide.

[0054] Figure 1 The SEM image of the nano-cobalt tetroxide provided in Example 1 is shown. Figure 1 It can be seen that the overall size of the nanoparticles is uniform, the diameter distance is small, and the particles have no obvious agglomeration.

[0055] Example 2

[0056] This embodiment provides a method for preparing nano-cobalt tetroxide, and the preparation method is as follows:

[0057] S1: First, prepare cobalt chloride salt into solution A with a Co concentration of 80g / L, and prepare 210g / L ammonium carbonate solution B;

[0058] S2: Pure water and solution B are added as the reaction base liquid, and the feed flow rate of solution A and solution B is simultaneously introduced into the reactor at a ratio of 1:0.01 to carry out a coprecipitation reaction. During the reaction, the feed amount of solution A and solution B is adjusted to ensure the stability of the process pH value. The reaction temperature is controlled at 70°C, the pH is controlled at 7.1, and the rotation speed is 300r / min. When the median particle size D50 reaches 100nm, the reactor is stopped to obtain a reaction slurry after the coprecipitation reaction;

[0059] S3: The reaction slurry is transferred to an aging tank and aged at 60° C. The aged material is washed with hot water at 80° C. and then dried at 100° C. to obtain a cobalt carbonate intermediate material with a median particle size D50 of 100 nm;

[0060] S4: The cobalt carbonate intermediate material and the grain growth inhibitor VC are added to a mixer at a mass ratio of 1:0.001 and mixed evenly. In a mixed gas environment of nitrogen and air, the temperature is raised to 450° C. at a heating rate of 5° C. / min and the mixed material is calcined in a rotary kiln. The calcination stage is kept warm for 120 minutes, and then the heating is stopped to obtain the nano-cobalt tetroxide.

[0061] Example 3

[0062] This embodiment provides a method for preparing nano-cobalt tetroxide, and the preparation method is as follows:

[0063] S1: First, prepare cobalt chloride salt into solution A with a Co concentration of 160g / L, and prepare 260g / L ammonium carbonate solution B;

[0064] S2: Pure water and solution B are added as the reaction base liquid, and the feed flow rate of solution A and solution B is simultaneously introduced into the reactor at a ratio of 1:3 to carry out a coprecipitation reaction. During the reaction, the feed amount of solution A and solution B is adjusted to ensure the stability of the process pH value. The reaction temperature is controlled at 35°C, the pH is controlled at 9, and the rotation speed is 150r / min. When the reaction reaches a median particle size D50 of 800nm, the reactor is stopped to obtain a reaction slurry after the coprecipitation reaction;

[0065] S3: The reaction slurry is transferred to an aging tank and aged at 60° C. The aged material is washed with hot water at 80° C. and then dried at 100° C. to obtain a cobalt carbonate intermediate material with a median particle size D50 of 800 nm;

[0066] S4: The cobalt carbonate intermediate material and the grain growth inhibitor Cr3C2 are added to a mixer at a mass ratio of 1:0.01 and mixed evenly. In a mixed gas environment of nitrogen and air, the temperature is raised to 700°C at a heating rate of 20°C / min and the mixed material is calcined in a rotary kiln. The calcination stage is kept warm for 30 minutes, and then the heating is stopped to obtain the nano-cobalt tetroxide.

[0067] Example 4

[0068] The difference between this embodiment and embodiment 1 is that the crystal growth inhibitor in step S4 of this embodiment is Nb2O5.

[0069] The rest of the preparation methods and parameters were the same as those in Example 1.

[0070] Example 5

[0071] The difference between this embodiment and embodiment 1 is that in step S4 of this embodiment, the mass ratio of the cobalt carbonate intermediate material to the grain growth inhibitor VC is 1:0.001.

[0072] The rest of the preparation methods and parameters were the same as those in Example 1.

[0073] Example 6

[0074] The difference between this embodiment and embodiment 1 is that in step S4 of this embodiment, the mass ratio of the cobalt carbonate intermediate material to the grain growth inhibitor VC is 1:0.01.

[0075] The rest of the preparation methods and parameters were the same as those in Example 1.

[0076] Example 7

[0077] The difference between this embodiment and embodiment 1 is that in step S2 of this embodiment, when the median particle size D50 reaches 1.5 μm, the reaction vessel is stopped to obtain a reaction slurry after the coprecipitation reaction.

[0078] The rest of the preparation methods and parameters were the same as those in Example 1.

[0079] Example 8

[0080] The difference between this embodiment and embodiment 1 is that in step S4 of this embodiment, the mass ratio of the cobalt carbonate intermediate material to the grain growth inhibitor VC is 1:0.0005.

[0081] The rest of the preparation methods and parameters were the same as those in Example 1.

[0082] Example 9

[0083] The difference between this embodiment and embodiment 1 is that in step S4 of this embodiment, the mass ratio of the cobalt carbonate intermediate material to the grain growth inhibitor VC is 1:0.015.

[0084] The rest of the preparation methods and parameters were the same as those in Example 1.

[0085] Example 10

[0086] The difference between this embodiment and embodiment 1 is that the calcination in step S4 of this embodiment is carried out in a muffle furnace and is static sintering.

[0087] The rest of the preparation methods and parameters were the same as those in Example 1.

[0088] Comparative Example 1

[0089] The difference between this comparative example and Example 1 is that in step S4 of this comparative example, no crystal growth inhibitor is added, and the cobalt carbonate intermediate material is directly calcined.

[0090] The rest of the preparation methods and parameters were the same as those in Example 1.

[0091] The particle sizes of the nano-cobalt tetroxide provided in Examples 1-10 and Comparative Example 1 were tested using a laser diffraction particle size analyzer. The test results are shown in Table 1.

[0092] Table 1

[0093]

[0094] From Table 1 we can conclude that:

[0095] The preparation method provided by the present invention is used to prepare nano-cobalt tetroxide, thereby preparing nano-scale cobalt tetroxide with a small particle size, uniform distribution, and narrow diameter spacing. By further controlling the median particle size D50 of cobalt carbonate obtained by the coprecipitation method and the amount of crystal growth inhibitor added, nano-scale cobalt tetroxide with an even smaller particle size, more uniform distribution, and narrower diameter spacing can be obtained.

[0096] In summary, the present invention first prepares a cobalt carbonate intermediate material with finer primary grains through a coprecipitation method, and then adds a grain growth inhibitor for calcination to prevent the grains from fusing with each other during the calcination process, thereby fusing small grains into large particles and avoiding particle agglomeration, thereby preparing nano-scale cobalt trioxide with smaller particle size, more uniform distribution and narrower diameter distance; and can achieve continuous production; the preparation process is simple and easy to operate, and is suitable for large-scale production.

[0097] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing nano-cobalt tetroxide, characterized in that: The preparation method comprises the following steps: (1) mixing a cobalt salt solution and a precipitant solution, and performing a coprecipitation reaction to obtain a cobalt carbonate intermediate material; (2) Mixing a cobalt carbonate intermediate material and a crystal growth inhibitor, and sintering to obtain the nano-cobalt tetroxide.

2. The preparation method according to claim 1, characterized in that The concentration of cobalt ions in the cobalt salt solution in step (1) is 80 g / L to 160 g / L; Preferably, the concentration of the precipitant solution in step (1) is 210 g / L to 260 g / L; Preferably, in step (2), the feed flow ratio of the cobalt salt solution and the precipitant solution is 1:(0.1-3); Preferably, the mixed raw materials in step (1) also include a dopant solution.

3. The preparation method according to claim 1, characterized in that The reaction temperature of the coprecipitation reaction in step (1) is 35° C. to 70° C., the pH value of the coprecipitation reaction is 7 to 9, and the rotation speed of the coprecipitation reaction is 100 r / min to 450 r / min; Preferably, after the coprecipitation reaction in step (1) is completed, aging, washing and drying are carried out in sequence.

4. The preparation method according to claim 1, characterized in that The median particle size D50 of the cobalt carbonate intermediate material in step (1) is ≥100 nm, preferably 100 nm to 1 μm.

5. The preparation method according to claim 1, characterized in that The mass ratio of the cobalt carbonate intermediate material to the crystal growth inhibitor in step (2) is 1:(0.001-0.01); Preferably, the crystal growth inhibitor in step (2) includes any one of VC, Cr3C2 or Nb2O5, or a combination of at least two of them.

6. The preparation method according to claim 1, characterized in that The heating rate of the sintering in step (2) is 5°C / min to 20°C / min, the holding temperature of the sintering is 450°C to 700°C, and the holding time of the sintering is 30min to 120min; Preferably, the sintering in step (2) is carried out in an oxygen-containing atmosphere.

7. The preparation method according to claim 1 or 6, characterized in that The sintering method in step (2) includes dynamic sintering.

8. The preparation method according to claim 1, characterized in that The median particle size D50 of the nano-cobalt tetroxide in step (2) is 200nm to 600nm.

9. A nano-cobalt tetroxide, characterized in that: The nano-cobalt tetroxide is prepared by the preparation method according to any one of claims 1 to 8.

10. A use of nano-cobalt tetroxide, characterized in that: The use includes using the nano-cobalt tetroxide according to claim 9 in any one or at least two of the fields of new energy, catalysis or electronic devices.

Images