Cobalt carbonate, nanometer cobaltosic oxide, preparation method and battery

Abstract

The invention relates to cobalt carbonate, nano cobaltosic oxide, a preparation method and a battery, and the preparation method comprises the following steps: mixing a solvent, ammonium bicarbonate, an auxiliary solvent and a dispersing agent to obtain a base solution with the pH value of 7.5-8.4; the volume ratio of the solvent to the auxiliary solvent is (5.5: 1)-(6.5: 1); the concentration of the dispersing agent in the base solution is 0.4 g / L to 0.6 g / L; a cobalt salt solution and an ammonium bicarbonate solution are introduced into the base solution in a parallel flow mode, a co-precipitation reaction is carried out till the particle size D50 reaches 0.3-2 microns, then aging, solid-liquid separation, washing and drying are carried out, and cobalt carbonate is obtained. The auxiliary solvent and the dispersing agent are added into the base solution, so that cobalt carbonate which is uniform in particle size, regular in morphology and small in particle size can be obtained; and the preparation method is simple to operate, the production efficiency can be improved, and the production cost can be reduced.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a positive electrode material, particularly to a cobalt carbonate, nano-cobalt tetroxide, preparation method and battery. Background Technology

[0002] Ultrafine powders, also known as nanoparticles, typically refer to tiny solid particles with a diameter ranging from 1 nm to 100 nm. As materials become increasingly ultrafine, their surface electronic and crystal structures change, resulting in surface effects, small-size effects, quantum effects, and macroscopic quantum tunneling effects not found in ordinary particles. This gives ultrafine powders a series of superior physical and chemical properties compared to conventional particulate materials. Ultrafine oxide powders are a new type of non-equilibrium material with high chemical activity, excellent optical properties, outstanding electrochemical properties, and magnetic properties. Metal oxide nanoparticles are a class of nanomaterials with wide applications in chemical engineering, electronics, food, biology, and medicine. Currently, research on metal oxide nanoparticles worldwide mainly focuses on four aspects: preparation, microstructure, macroscopic properties, and applications. Among these, the preparation technology of nanoparticles is crucial, as the preparation process and process control have a significant impact on the microstructure and macroscopic properties of nanoparticles.

[0003] Traditional methods for preparing nano-metal oxide powder materials mainly include precipitation, hydrolysis, solid-phase thermal decomposition, and chemical vapor deposition. In recent years, methods such as room-temperature solid-phase reaction, sol-gel, microemulsion, hydrothermal, solvothermal, and radiation synthesis have been developed. The electrochemical performance of a substance is related not only to particle size and distribution but also to its morphology. Nanoscale Co3O4 exhibits superior electrochemical performance compared to micron-sized Co3O4, and cubic Co3O4 outperforms other morphologies of cobalt tetroxide. The solvothermal synthesis method offers advantages such as mild reaction conditions, high product purity, well-developed crystals, small and uniform particle size distribution, no agglomeration, good dispersibility, and controllable shape, attracting widespread attention from researchers both domestically and internationally.

[0004] However, in the existing technology, the cobalt tetroxide used in ultrafine cobalt powder is generated by calcining fine cobalt carbonate particles. After sintering, fine cobalt carbonate particles are prone to agglomeration and have low yield. In addition, the morphology of the prepared nano cobalt tetroxide is poor and large particles are easy to appear.

[0005] CN108264095A discloses a method for preparing battery-grade spherical cobalt carbonate. The method involves simultaneously adding ammonium bicarbonate solution and cobalt salt solution to a reaction vessel containing ammonium bicarbonate as a base solution. The reaction temperature and stirring speed are adjusted, and the addition rate of the cobalt salt solution is kept constant. The pH value is controlled to be 7.2–7.5 within 1 hour of nucleation and 7.0–7.4 after 12 hours, with the reaction lasting 22–26 hours. The ammonium bicarbonate solution and cobalt salt solution are then added simultaneously, with the reaction temperature and stirring speed adjusted, the addition rate of the cobalt salt solution intermittently increased, and the pH value of the crystallization reaction kept constant. The reaction continues until the cobalt carbonate grows to a predetermined size. While the resulting cobalt carbonate exhibits high sphericity and uniform particle distribution, the particle size (D50) is as high as 16 μm–20 μm, making it unsuitable for preparing cobalt carbonate and cobalt tetroxide with smaller particle sizes.

[0006] To address the shortcomings of existing technologies, there is a need to provide a method for preparing cobalt carbonate, nano-cobalt tetroxide, and a battery. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing cobalt carbonate, nano-cobalt tetroxide, and a battery. By adding an auxiliary solvent and a dispersant to the base liquid, the present invention can obtain cobalt carbonate with uniform particle size, regular morphology, and small particle size. Moreover, the preparation method of the present invention is simple to operate, which is conducive to improving production efficiency and reducing production costs.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing cobalt carbonate, the method comprising the following steps:

[0010] (1) Mix the solvent, ammonium bicarbonate, auxiliary solvent and dispersant to obtain a base solution with a pH of 7.5 to 8.4;

[0011] The volume ratio of the solvent to the auxiliary solvent is 5.5:1 to 6.5:1;

[0012] The concentration of the dispersant in the base liquid is 0.4 g / L to 0.6 g / L;

[0013] (2) Cobalt salt solution and ammonium bicarbonate solution are introduced into the bottom liquid in parallel and co-precipitated until the particle size D50 reaches 0.3μm~2μm. Then, the mixture is aged, separated from the solid liquid, washed and dried to obtain the cobalt carbonate.

[0014] This invention, by adding an auxiliary solvent and a dispersant to the base solution, can obtain cobalt carbonate with uniform particle size, regular morphology, and small particle size. Specifically, the auxiliary solvent and dispersant in the base solution generate cobalt carbonate with good sphericity and high dispersibility in primary particles, which is beneficial for obtaining spherical nano-sized cobalt tetroxide with good flowability. Moreover, the preparation method of this invention is simple to operate, which is conducive to improving production efficiency and reducing production costs.

[0015] Preferably, the solvent is water.

[0016] Preferably, the auxiliary solvent includes any one or a combination of at least two of ethanol, ethylene glycol, or n-butanol.

[0017] Preferably, the dispersant comprises any one or a combination of at least two of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or polyethylene glycol.

[0018] Preferably, the cobalt salt in the cobalt salt solution includes any one or a combination of at least two of cobalt chloride, cobalt nitrate, or cobalt sulfate.

[0019] Preferably, the cobalt ion concentration in the cobalt salt solution is 110 g / L to 130 g / L.

[0020] Preferably, the concentration of the ammonium bicarbonate solution is 180 g / L to 230 g / L.

[0021] Preferably, during the coprecipitation reaction, the flow rate of the cobalt salt solution is 100 L / h to 300 L / h.

[0022] Preferably, during the coprecipitation reaction, the flow rate of the ammonium bicarbonate solution is 130 L / h to 450 L / h.

[0023] Preferably, the temperature of the coprecipitation reaction is 36℃~45℃.

[0024] Preferably, the coprecipitation reaction is carried out under stirring conditions of 300 r / min to 450 r / min.

[0025] Preferably, the washing is performed using an ammonium bicarbonate washing solution.

[0026] In a second aspect, the present invention provides cobalt carbonate, which is prepared by the preparation method described in the first aspect.

[0027] Thirdly, the present invention provides a method for preparing nano-cobalt tetroxide, the method comprising: calcining the cobalt carbonate described in the second aspect in an oxygen-containing atmosphere to obtain the nano-cobalt tetroxide.

[0028] Fourthly, the present invention provides a nano-cobalt tetroxide, which is prepared by the preparation method described in the third aspect.

[0029] Fifthly, the present invention provides a battery comprising the nano-cobalt tetroxide described in the fourth aspect.

[0030] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

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

[0032] This invention, by adding an auxiliary solvent and a dispersant to the base solution, can obtain cobalt carbonate with uniform particle size, regular morphology, and small particle size. Specifically, the auxiliary solvent and dispersant in the base solution generate cobalt carbonate with good sphericity and high dispersibility in primary particles, which is beneficial for obtaining spherical nano-sized cobalt tetroxide with good flowability. Moreover, the preparation method of this invention is simple to operate, which is conducive to improving production efficiency and reducing production costs. Detailed Implementation

[0033] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0034] An embodiment of the present invention provides a method for preparing cobalt carbonate, the method comprising the following steps:

[0035] (1) Mix the solvent, ammonium bicarbonate, auxiliary solvent and dispersant to obtain a base solution with a pH of 7.5 to 8.4;

[0036] The volume ratio of the solvent to the auxiliary solvent is 5.5:1 to 6.5:1;

[0037] The concentration of the dispersant in the base liquid is 0.4 g / L to 0.6 g / L;

[0038] (2) Cobalt salt solution and ammonium bicarbonate solution are introduced into the bottom liquid in parallel and co-precipitated until the particle size D50 reaches 0.3μm~2μm. Then, the mixture is aged, separated from the solid liquid, washed and dried to obtain the cobalt carbonate.

[0039] This invention, by adding an auxiliary solvent and a dispersant to the base solution, can obtain cobalt carbonate with uniform particle size, regular morphology, and small particle size. Specifically, the auxiliary solvent and dispersant in the base solution generate cobalt carbonate with good sphericity and high dispersibility in primary particles, which is beneficial for obtaining spherical nano-sized cobalt tetroxide with good flowability. Moreover, the preparation method of this invention is simple to operate, which is conducive to improving production efficiency and reducing production costs.

[0040] In this invention, the pH value of the base solution is adjusted by the amount of ammonium bicarbonate used, and is 7.5 to 8.4. For example, it can be 7.5, 7.6, 7.8, 8, 8.2 or 8.4, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] In this invention, the volume ratio of solvent to auxiliary solvent is 5.5:1 to 6.5:1, for example, it can be 5.5, 5.8, 6, 6.2, 6.4 or 6.5, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] The auxiliary solvent in this invention is less polar than water. When the amount of auxiliary solvent is small, the solvent system is dominated by highly polar water, which will lead to rapid precipitation, insufficient crystallization time, possible mixing of amorphous phases in the product, and insufficient surface modification. When the amount of auxiliary solvent is too large, it will lead to a slow nucleation rate, resulting in the formation of particles with excessively large or agglomerated particle size, which is not conducive to obtaining cobalt carbonate with uniform morphology.

[0043] In this invention, the concentration of the dispersant in the base liquid is 0.4 g / L to 0.6 g / L, for example, it can be 0.4 g / L, 0.5 g / L or 0.6 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] In this invention, the use of an auxiliary solvent reduces the polarity of the solvent system, thereby lowering the surface energy of cobalt carbonate and reducing the tendency for aggregation driven by high surface energy between particles. The dispersant, in addition to this, further blocks particle contact through charge repulsion and steric hindrance. Together, these factors significantly improve the dispersion stability of the reaction system, making it easier for cobalt carbonate to form uniform small particles. However, when the initial concentration of the dispersant is too low, the surface of the cobalt carbonate crystal nuclei cannot be fully covered by the dispersant, posing a risk of aggregation. Conversely, when the initial concentration of the dispersant is too high, it can inhibit crystal nucleus growth, posing a risk of producing deformed particles. Therefore, the concentration of the dispersant in the base solution is 0.4 g / L to 0.6 g / L.

[0045] Moreover, the present invention does not add an additional dispersant during the coprecipitation reaction, so that the concentration of the dispersant in the system gradually decreases, allowing the cobalt carbonate crystal nuclei to grow stably, which is beneficial to obtaining cobalt carbonate with good morphology, uniform particle size and small particle size.

[0046] In some embodiments, the solvent is water.

[0047] In some embodiments, the auxiliary solvent includes any one or a combination of at least two of ethanol, ethylene glycol, or n-butanol. Typical but non-limiting combinations include combinations of ethanol and ethylene glycol, ethanol and n-butanol, ethylene glycol and n-butanol, or ethanol, ethylene glycol, and n-butanol.

[0048] In some embodiments, the dispersant comprises any one or a combination of at least two of sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), or polyethylene glycol (PEG). Typical but non-limiting combinations include combinations of SDS and SDBS, SDS and PEG, SDBS and PEG, or combinations of SDS, SDBS, and PEG.

[0049] In some embodiments, the cobalt salt in the cobalt salt solution includes any one or a combination of at least two of cobalt chloride, cobalt nitrate, or cobalt sulfate. Typical but non-limiting combinations include a combination of cobalt chloride and cobalt nitrate, a combination of cobalt chloride and cobalt sulfate, a combination of cobalt nitrate and cobalt sulfate, or a combination of cobalt chloride, cobalt nitrate, and cobalt sulfate.

[0050] In some embodiments, the cobalt ion concentration in the cobalt salt solution is 110 g / L to 130 g / L, for example, it can be 110 g / L, 115 g / L, 120 g / L, 125 g / L or 130 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0051] In some embodiments, the concentration of the ammonium bicarbonate solution is 180 g / L to 230 g / L, for example, it can be 180 g / L, 200 g / L, 210 g / L, 220 g / L or 230 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0052] In some embodiments, during the coprecipitation reaction, the flow rate of the cobalt salt solution is 100 L / h to 300 L / h, for example, it can be 100 L / h, 150 L / h, 200 L / h, 250 L / h or 300 L / h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0053] In some embodiments, during the coprecipitation reaction, the flow rate of the ammonium bicarbonate solution is 130 L / h to 450 L / h, for example, it can be 130 L / h, 150 L / h, 200 L / h, 250 L / h, 300 L / h, 350 L / h, 400 L / h or 450 L / h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0054] Within the flow rate range of the cobalt salt solution and ammonium bicarbonate solution provided by this invention, the pH value during the coprecipitation reaction is 7.4 to 8.6.

[0055] For example, the coprecipitation reaction described in this invention is carried out in a reaction vessel with a size of 50L to 200L. Under the reaction conditions of this invention, the time required for the coprecipitation reaction to reach a particle size D50 of 0.3μm to 2μm is approximately 2h to 5h.

[0056] In some embodiments, the temperature of the coprecipitation reaction is 36°C to 45°C, for example, 36°C, 38°C, 40°C, 42°C or 45°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] In some embodiments, the coprecipitation reaction is carried out under stirring conditions of 300 r / min to 450 r / min, for example, 300 r / min, 320 r / min, 350 r / min, 360 r / min, 400 r / min, 420 r / min or 450 r / min, but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0058] In some embodiments, the washing is performed using an ammonium bicarbonate washing solution.

[0059] In some embodiments, the concentration of the ammonium bicarbonate washing solution is 30 g / L to 75 g / L, for example, it can be 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L or 75 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0060] In some embodiments, the washing temperature range is 20°C to 80°C, for example, it can be 20°C, 30°C, 40°C, 50°C, 60°C or 80°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0061] In some embodiments, the drying temperature range is 100°C to 150°C, for example, it can be 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0062] As a preferred embodiment of the present invention, the method for preparing cobalt carbonate includes the following steps:

[0063] This embodiment provides a method for preparing cobalt carbonate, the method comprising the following steps:

[0064] (1) Prepare a cobalt sulfate solution with a cobalt ion concentration of 110 g / L to 130 g / L and an ammonium bicarbonate solution with a concentration of 180 g / L to 230 g / L;

[0065] A mixture of water, ammonium bicarbonate, auxiliary solvent, and dispersant was prepared to obtain a base solution with a pH value of 7.5–8.4; wherein the volume ratio of water to auxiliary solvent was 5.5:1–6.5:1; and the concentration of dispersant in the base solution was 0.4 g / L–0.6 g / L.

[0066] The auxiliary solvent includes any one or a combination of at least two of ethanol, ethylene glycol, or n-butanol; the dispersant includes any one or a combination of at least two of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or polyethylene glycol.

[0067] (2) Add bottom liquid to a 200L reactor, the volume of which is 40% to 55% of the reactor volume; then introduce cobalt sulfate solution and ammonium bicarbonate solution into the bottom liquid in parallel, and co-precipitate at 36℃ to 45℃ and stirring speed of 300r / min to 450r / min until the particle size D50 reaches 0.3μm to 2μm;

[0068] The flow rate of cobalt sulfate solution is 100 L / h to 300 L / h; the flow rate of ammonium bicarbonate solution is 130 L / h to 450 L / h.

[0069] (3) Aging for 1-3 hours, solid-liquid separation, washing and drying to obtain the cobalt carbonate;

[0070] Washing is performed using an ammonium bicarbonate washing solution with a concentration of 30 g / L to 75 g / L at a temperature of 20°C to 80°C; drying is performed at a temperature range of 100°C to 150°C.

[0071] One embodiment of the present invention provides cobalt carbonate, which is prepared by the preparation method described in any embodiment.

[0072] An embodiment of the present invention provides a method for preparing nano-cobalt tetroxide, the method comprising: calcining cobalt carbonate as described in any embodiment in an oxygen-containing atmosphere to obtain the nano-cobalt tetroxide.

[0073] For example, the gas used in the oxygen-containing atmosphere includes oxygen and / or air.

[0074] One embodiment of the present invention provides a nano-cobalt tetroxide, which is prepared by the preparation method described in any embodiment.

[0075] One embodiment of the present invention provides a battery comprising the nano-cobalt tetroxide described in any embodiment.

[0076] Example 1

[0077] This embodiment provides a method for preparing cobalt carbonate, the method comprising the following steps:

[0078] (1) Prepare a cobalt sulfate solution with a cobalt ion concentration of 120 g / L and an ammonium bicarbonate solution with a concentration of 200 g / L;

[0079] Water, ammonium bicarbonate, auxiliary solvent, and dispersant were mixed to obtain a base solution with a pH of 8; wherein the volume ratio of water to auxiliary solvent was 6:1; and the concentration of dispersant in the base solution was 0.5 g / L.

[0080] The auxiliary solvent is ethanol; the dispersant is PEG-400.

[0081] (2) Add bottom liquid to a 200L reactor, the volume of which is 50% of the reactor volume; then introduce cobalt sulfate solution and ammonium bicarbonate solution into the bottom liquid in parallel, and co-precipitate the mixture at 40℃ and a stirring speed of 400r / min until the particle size D50 reaches 1μm.

[0082] The flow rate of the cobalt sulfate solution is 200 L / h; the flow rate of the ammonium bicarbonate solution is 300 L / h.

[0083] (3) After aging for 2 hours, solid-liquid separation, washing and drying, the cobalt carbonate is obtained;

[0084] Washing was performed using a 50 g / L ammonium bicarbonate washing solution at a temperature of 50°C; drying was carried out at a temperature range of 120°C.

[0085] Example 2

[0086] This embodiment provides a method for preparing cobalt carbonate, the method comprising the following steps:

[0087] (1) Prepare a cobalt sulfate solution with a cobalt ion concentration of 110 g / L and an ammonium bicarbonate solution with a concentration of 180 g / L;

[0088] Water, ammonium bicarbonate, auxiliary solvent, and dispersant were mixed to obtain a base solution with a pH of 7.5; wherein the volume ratio of water to auxiliary solvent was 5.5:1; and the concentration of dispersant in the base solution was 0.4 g / L.

[0089] The auxiliary solvent is ethanol; the dispersant is PEG-400.

[0090] (2) Add bottom liquid to a 200L reactor, the volume of which is 40% of the reactor volume; then introduce cobalt sulfate solution and ammonium bicarbonate solution into the bottom liquid in parallel, and co-precipitate the mixture at 36℃ and a stirring speed of 300r / min until the particle size D50 reaches 0.3μm.

[0091] The flow rate of the cobalt sulfate solution is 100 L / h; the flow rate of the ammonium bicarbonate solution is 130 L / h.

[0092] (3) After aging for 1 hour, solid-liquid separation, washing and drying, the cobalt carbonate is obtained;

[0093] Washing was performed using a 30 g / L ammonium bicarbonate washing solution at a temperature of 20°C; drying was carried out at a temperature range of 100°C.

[0094] Example 3

[0095] This embodiment provides a method for preparing cobalt carbonate, the method comprising the following steps:

[0096] (1) Prepare a cobalt sulfate solution with a cobalt ion concentration of 130 g / L and an ammonium bicarbonate solution with a concentration of 230 g / L;

[0097] A mixture of water, ammonium bicarbonate, auxiliary solvent, and dispersant was used to obtain a base solution with a pH of 8.4; wherein the volume ratio of water to auxiliary solvent was 6.5:1; and the concentration of dispersant in the base solution was 0.6 g / L.

[0098] The auxiliary solvent is ethanol; the dispersant is PEG-400.

[0099] (2) Add bottom liquid to a 200L reactor, the volume of which is 55% of the reactor volume; then introduce cobalt sulfate solution and ammonium bicarbonate solution into the bottom liquid in parallel, and co-precipitate at 45°C and stirring speed of 450r / min until the particle size D50 reaches 2μm.

[0100] The flow rate of the cobalt sulfate solution is 300 L / h; the flow rate of the ammonium bicarbonate solution is 450 L / h.

[0101] (3) After aging for 3 hours, solid-liquid separation, washing and drying, the cobalt carbonate is obtained;

[0102] Washing was performed using an ammonium bicarbonate washing solution with a concentration of 75 g / L at a temperature of 80°C; drying was carried out at a temperature range of 150°C.

[0103] Example 4

[0104] This embodiment provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that the auxiliary solvent is ethylene glycol.

[0105] Example 5

[0106] This embodiment provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that the auxiliary solvent is n-butanol.

[0107] Example 6

[0108] This embodiment provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that the dispersant is sodium dodecyl sulfate.

[0109] Example 7

[0110] This embodiment provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that the dispersant is sodium dodecylbenzenesulfonate.

[0111] Comparative Example 1

[0112] This comparative example provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that the volume ratio of water to auxiliary solvent is 5:1.

[0113] Comparative Example 2

[0114] This comparative example provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that the volume ratio of water to auxiliary solvent is 7:1.

[0115] Comparative Example 3

[0116] This comparative example provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that the concentration of the dispersant in the substrate is 0.2 g / L.

[0117] Comparative Example 4

[0118] This comparative example provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that the concentration of the dispersant in the substrate is 0.8 g / L.

[0119] Comparative Example 5

[0120] This comparative example provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that the auxiliary solvent is replaced by an equal volume of water.

[0121] Comparative Example 6

[0122] This comparative example provides a method for preparing cobalt carbonate, which is the same as in Example 1 except that no dispersant is used.

[0123] Performance Characterization

[0124] The sphericity and particle size distribution span of the cobalt carbonate obtained in the above examples and comparative examples were measured, where span = (D90 - D10) / D50. The smaller the value of span, the more concentrated the particle size distribution. The measurement results are shown in Table 1. Good, relatively good, relatively poor, and poor indicate the relative level of sphericity. Good sphericity is better than relatively good sphericity, relatively good sphericity is better than relatively poor sphericity, and relatively poor sphericity is better than poor sphericity.

[0125] Table 1

[0126] sphericity span Example 1 good 0.36 Example 2 good 0.41 Example 3 good 0.43 Example 4 better 0.58 Example 5 better 0.55 Example 6 better 0.53 Example 7 better 0.61 Comparative Example 1 Poor 0.72 Comparative Example 2 Poor 0.75 Comparative Example 3 Poor 0.79 Comparative Example 4 Poor 0.74 Comparative Example 5 Difference 0.85 Comparative Example 6 Difference 0.89

[0127] The cobalt carbonate obtained in the above examples and comparative examples was calcined in air at a temperature of 550°C to obtain cobalt tetroxide; cobalt tetroxide was mixed with lithium carbonate, and the molar ratio of Li to Co was controlled to be 1.06:1, and then solid-state sintering was carried out at a temperature of 1000°C for 12 hours to obtain lithium cobalt oxide cathode material.

[0128] Lithium cobalt oxide cathode material, acetylene black, and PVDF were mixed in a molar ratio of 92:4:4 and added to NMP to obtain a cathode slurry. The cathode slurry was then coated onto aluminum foil to obtain a cathode sheet. The lithium sheet was used as the anode sheet, and the CR2430 button cell was fabricated in an argon-filled glove box.

[0129] The button cell batteries were assembled and charged and discharged. The test voltage was 3V-4.4V. The first discharge specific capacity at 0.1C rate and the cycle capacity retention rate after 500 charge and discharge cycles at 0.1C rate were recorded. The results are shown in Table 2.

[0130] Table 2

[0131]

[0132]

[0133] In summary, by adding an auxiliary solvent and a dispersant to the base solution, this invention can obtain cobalt carbonate with uniform particle size, regular morphology, and small particle size. Specifically, the auxiliary solvent and dispersant in the base solution generate cobalt carbonate with good sphericity and high dispersibility in primary particles, which is beneficial for obtaining spherical nano-sized cobalt tetroxide with good flowability. Moreover, the preparation method of this invention is simple to operate, which helps to improve production efficiency and reduce production costs.

[0134] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing cobalt carbonate, characterized in that, The preparation method includes the following steps: (1) Mix the solvent, ammonium bicarbonate, auxiliary solvent and dispersant to obtain a base solution with a pH of 7.5 to 8.4; The volume ratio of the solvent to the auxiliary solvent is 5.5:1 to 6.5:1; The concentration of the dispersant in the base liquid is 0.4 g / L to 0.6 g / L; (2) Cobalt salt solution and ammonium bicarbonate solution are introduced into the bottom liquid in parallel and co-precipitated until the particle size D50 reaches 0.3μm~2μm. Then, the mixture is aged, separated from the solid liquid, washed and dried to obtain the cobalt carbonate.

2. The preparation method according to claim 1, characterized in that, The solvent is water.

3. The preparation method according to claim 1 or 2, characterized in that, The auxiliary solvent includes any one or a combination of at least two of ethanol, ethylene glycol, or n-butanol.

4. The preparation method according to any one of claims 1-3, characterized in that, The dispersant includes any one or a combination of at least two of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or polyethylene glycol.

5. The preparation method according to any one of claims 1-4, characterized in that, The cobalt salt in the cobalt salt solution includes any one or a combination of at least two of cobalt chloride, cobalt nitrate, or cobalt sulfate. And / or, the cobalt ion concentration in the cobalt salt solution is 110 g / L to 130 g / L; And / or, the concentration of the ammonium bicarbonate solution is 180 g / L to 230 g / L; And / or, during the coprecipitation reaction, the flow rate of the cobalt salt solution is 100 L / h to 300 L / h; And / or, during the coprecipitation reaction, the flow rate of the ammonium bicarbonate solution is 130 L / h to 450 L / h.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The temperature of the coprecipitation reaction is 36℃~45℃; And / or, the coprecipitation reaction is carried out under stirring conditions at a speed of 300 r / min to 450 r / min; And / or, the washing is performed using ammonium bicarbonate washing solution.

7. A cobalt carbonate, characterized in that, The cobalt carbonate is prepared by the preparation method described in any one of claims 1 to 6.

8. A method for preparing nano-cobalt tetroxide, characterized in that, The preparation method includes: calcining the cobalt carbonate of claim 7 in an oxygen-containing atmosphere to obtain the nano-cobalt tetroxide.

9. A nano-cobalt tetroxide, characterized in that, The nano-cobalt tetroxide is prepared by the preparation method described in claim 8.

10. A battery, characterized in that, The battery comprises the nano-cobalt tetroxide as described in claim 9.

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