Aluminum-doped cobalt precursor and its preparation method and application

Abstract

The present invention discloses an aluminum-doped cobalt precursor and a preparation method and application thereof. The preparation method comprises the following steps: stirring a mixed solution of cobalt salt and aluminum salt with a precipitant solution, then stopping stirring to obtain a reaction system; heating the reaction system to allow the product to grow, and collecting the aluminum-doped cobalt precursor. The present invention does not introduce additional surfactants and complexing agent structure adjustment agents, but only mixes the mixed solution of aluminum salt and cobalt salt with a precipitant solution. By adjusting the ratio of the mixed solution of aluminum salt and cobalt salt to the precipitant solution, the type and morphology of the product can be effectively controlled. The present invention stops stirring after the mixed solution of aluminum salt and cobalt salt is stirred with the precipitant solution to obtain a reaction system, and allows the system to stand and heat for growth, thereby avoiding problems such as poor crystal consistency caused by unstable continuous feeding of a metering pump; the reaction process is small, and the requirements for personnel and equipment are low, which is conducive to stable product production, while reducing manpower and electricity costs.

Description

Technical Field

[0001] The present invention relates to the technical field of cobalt carbonate materials, and in particular to an aluminum-doped cobalt precursor, a preparation method thereof, and applications thereof. Background Art

[0002] Cobalt carbonate and basic cobalt carbonate can serve not only as precursors for battery materials like cobalt trioxide and lithium cobaltate, but also as catalyst precursors. Whether used as precursors for battery materials or catalysts, these derivatives significantly inherit the properties of cobalt carbonate and basic cobalt carbonate. For example, aluminum doping in cobalt carbonate and basic cobalt carbonate can improve the stability of the derived lithium cobaltate cathode materials. Furthermore, the morphology and particle size of cobalt carbonate and basic cobalt carbonate also significantly influence the discharge performance of the derived lithium cobaltate cathode materials.

[0003] To this end, researchers have conducted extensive research on aluminum-doped cobalt carbonate and basic cobalt carbonate. CN118811868A discloses a method for preparing an aluminum-doped basic cobalt carbonate material. The method comprises the following steps: first, a cobalt salt, an aluminum salt, and a nonionic surfactant are mixed to form a mixed solution 1; then, an ammonium bicarbonate solution and an ammonia-ammonium chloride buffer solution are mixed to form a mixed solution 2; then, the mixed solution 1 and the mixed solution 2 are mixed, the pH is controlled, and the mixture is reacted under heating and stirring to obtain a seed solution; then, the mixed solution 1 and the mixed solution 2 are added to the seed solution, the pH is controlled, and the mixture is reacted under heating and stirring to obtain a quasi-spherical aluminum-doped basic cobalt carbonate. This method uses a nonionic surfactant to complex the cobalt ions, resulting in an orderly and slow precipitation of the cobalt ions. The ammonia-ammonium chloride buffer solution can effectively prevent the pH in the system from suddenly changing, thereby preparing aluminum-doped basic cobalt carbonate with good sphericity. However, this method requires strict control of the reaction pH, and the operation is relatively cumbersome. CN115477331A discloses a cobalt-aluminum-doped carbonate and its preparation method. A soluble cobalt salt, a soluble aluminum salt, and a dispersant are dissolved in water to obtain a molten metal A. A soluble cobalt salt and a soluble aluminum salt are dissolved in water to obtain a molten metal B. A bicarbonate is prepared as a base liquid, and a carbonate is prepared as a precipitant. The molten metal A and the precipitant are added to the base liquid in parallel, reacting to form a mixed system containing cobalt-aluminum-doped carbonate crystals. When the median particle size of the cobalt-aluminum-doped carbonate crystals reaches 14-15 μm, the addition of molten metal A to the mixed system is stopped, and the molten metal B and the precipitant are added to the mixed system in parallel to react to obtain spherical cobalt-aluminum-doped carbonate. This method can produce cobalt carbonate with a median particle size of up to 20 μm, but a dispersant is used for regulation and the stirring frequency must be strictly controlled.

[0004] It is necessary to provide a simple preparation method that does not require surfactants and complexing agents to regulate the structure of aluminum-doped cobalt precursors. Summary of the Invention

[0005] The present invention aims to prepare the desired aluminum-doped cobalt precursor by adjusting the ratio of a mixed solution of aluminum salt and cobalt salt to a precipitant solution without introducing additional surfactants and complexing agent structure adjustment agents, and growing the precursor at a lower temperature without further stirring after mixing.

[0006] In order to achieve the above object, the present invention provides a method for preparing an aluminum-doped cobalt precursor, comprising:

[0007] The mixed solution of the cobalt salt and the aluminum salt and the precipitant solution are stirred and then the stirring is stopped to obtain a reaction system;

[0008] The reaction system is heated to allow the product to grow, and the aluminum-doped cobalt precursor is collected.

[0009] Furthermore, the heating raises the temperature of the reaction system to 40-60°C;

[0010] The growth time is 15-20 hours.

[0011] Furthermore, the concentrations of the cobalt salt and the aluminum salt in the mixed solution of the cobalt salt and the aluminum salt are 90-150 g / L and 1.4-1.7 g / L, respectively.

[0012] Furthermore, the concentration of the precipitant in the precipitant solution is 200-260 g / L, and the precipitant includes at least one of a soluble carbonate and a soluble bicarbonate.

[0013] Furthermore, the volume ratio of the mixed solution of the cobalt salt and the aluminum salt to the precipitant solution is 1:0.4-1.4.

[0014] Furthermore, the stirring and mixing is continued for 1-2 hours at a rotation speed of 180-230 rpm.

[0015] Further, the collecting includes washing and drying;

[0016] The washing reduces the concentration of impurity ions in the washing liquid to less than 20 ppm;

[0017] The drying is carried out at 100-130°C.

[0018] It should be noted that the present invention does not strictly limit the types of cobalt salts and aluminum salts. For example, the cobalt salt can be at least one of cobalt chloride hexahydrate, cobalt sulfate heptahydrate, and cobalt nitrate hexahydrate; the aluminum salt can be at least one of aluminum nitrate nonahydrate, anhydrous aluminum chloride, and aluminum sulfate 18hydrate. The precipitant can be at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, and ammonium bicarbonate. The solvents for the mixed solution of the cobalt salt and aluminum salt and the precipitant solution are also not strictly limited. For example, they can be at least one of water, ethanol, and acetone, with water being preferred.

[0019] The present invention also provides an aluminum-doped cobalt precursor, which is obtained by the above method.

[0020] Furthermore, the morphology of the aluminum-doped cobalt precursor is nanosheet clusters or spherical.

[0021] The present invention also provides the use of the aluminum-doped cobalt precursor as a precursor of battery materials and catalysts.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention does not introduce additional surfactants and complexing agent structure adjustment additives, but only mixes the aluminum salt and cobalt salt mixed solution with the precipitant solution. By adjusting the ratio of the aluminum salt and cobalt salt mixed solution to the precipitant solution, the type and morphology of the product can be effectively controlled.

[0024] According to the present invention, after the mixed solution of aluminum salt and cobalt salt is stirred and mixed with the precipitant solution to obtain a reaction system, stirring is stopped and the system is allowed to stand and heat up for growth, thereby avoiding problems such as poor crystal consistency caused by unstable continuous feeding of a metering pump. The invention has fewer reaction processes and lower requirements on personnel and equipment, which is conducive to stable production of products. At the same time, the number of personnel operation steps and device stirring are reduced, thereby reducing labor and electricity costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A flow chart showing the method for preparing the aluminum-doped cobalt precursor of Example 1 is shown;

[0027] Figure 2 shows the XRD patterns of the aluminum-doped cobalt precursors prepared in Examples 1 to 10;

[0028] Figure 3 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 1;

[0029] Figure 4 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 2;

[0030] Figure 5 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 3;

[0031] Figure 6 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 4;

[0032] Figure 7 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 5;

[0033] Figure 8 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 6;

[0034] Figure 9 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 7;

[0035] Figure 10 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 8;

[0036] Figure 11 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 9;

[0037] Figure 12 The scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 10 is shown. DETAILED DESCRIPTION

[0038] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in the present invention.

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the specific embodiments of the present invention and the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] Example 1

[0041] like Figure 1 As shown, a method for preparing an aluminum-doped cobalt precursor comprises the following steps:

[0042] S1. Dissolving cobalt chloride hexahydrate and anhydrous aluminum chloride in water to prepare a mixed solution of cobalt salt and aluminum salt with a cobalt salt concentration of 130 g / L and an aluminum salt concentration of 1.5 g / L; dissolving ammonium bicarbonate in water to prepare a precipitant solution with an ammonium bicarbonate concentration of 230 g / L;

[0043] S2, stirring 1000 L of the mixed solution of the cobalt salt and the aluminum salt and 400 L of the precipitant solution at a speed of 220 rpm for 1.5 h, then stopping the stirring to obtain a reaction system;

[0044] S3. The reaction system was heated to 42° C. and allowed to stand for 20 h to allow the product to grow. The slurry was filtered and then filtered and washed with water until the concentrations of chloride ions and sodium ions in the water were lower than 20 ppm. The insoluble matter was then transferred to 120° C. for drying to obtain an aluminum-doped cobalt precursor.

[0045] Example 2-Example 10

[0046] The specific method can refer to Example 1, except that the volume ratio of the mixed solution of cobalt salt and aluminum salt to the precipitant solution is different. Table 1 lists the specific volume ratios of these examples.

[0047] Table 1 Volume ratio of the mixed solution of cobalt salt and aluminum salt and the precipitant solution in the embodiment

[0048]

[0049] Example 11

[0050] The process is basically the same as Example 1, except that cobalt nitrate hexahydrate is used instead of cobalt chloride hexahydrate in step S1.

[0051] Example 12

[0052] The process is basically the same as Example 1, except that aluminum nitrate nonahydrate is used instead of anhydrous aluminum chloride in step S1.

[0053] Example 13

[0054] The method is basically the same as Example 1, except that sodium bicarbonate is used instead of ammonium bicarbonate in step S1.

[0055] Example 14

[0056] The process is basically the same as Example 1, except that cobalt nitrate hexahydrate is used instead of cobalt chloride hexahydrate in step S1.

[0057] Example 15

[0058] The process is basically the same as Example 1, except that aluminum nitrate nonahydrate is used instead of anhydrous aluminum chloride in step S1.

[0059] Example 16

[0060] The method is basically the same as Example 1, except that sodium bicarbonate is used instead of ammonium bicarbonate in step S1.

[0061] Test Case

[0062] The crystal structures of the aluminum-doped cobalt precursors prepared in Examples 1-10 were tested using XRD. Figure 2 It can be seen that the volume ratio of the mixed solution of cobalt salt and aluminum salt to the precipitant solution is greater than 1:0.8, that is, when the pH is low, the aluminum-doped cobalt precursor is basic cobalt carbonate. When the volume ratio is 1:0.9-1.3, the aluminum-doped cobalt precursor is converted into cobalt carbonate.

[0063] The morphology of the aluminum-doped cobalt precursors prepared in Examples 1-10 was further tested using a scanning electron microscope. The results were as follows: Figure 3-Figure 12 As shown. It can be seen that the structures of the basic cobalt carbonates prepared in Examples 1 to 5 are all nanoclusters formed by the accumulation of nanosheets; the cobalt carbonates prepared in Examples 6 to 10 are spherical with a particle size of about 7-8 μm, especially when a mixed solution of cobalt salt and aluminum salt with a cobalt salt concentration of 130 g / L and an aluminum salt concentration of 1.5 g / L is mixed with an ammonium bicarbonate solution with a concentration of 230 g / L in a volume ratio of 1:1 and then allowed to grow statically. Figure 9 ) have the most regular shape and less surface agglomeration. In Examples 8-10, the amount of ammonium bicarbonate solution is large, and a large number of spherical cobalt carbonates have small cobalt carbonate particles attached to the surface.

[0064] These results demonstrate that the present invention successfully achieves this by stirring a mixed solution of cobalt salt and aluminum salt with a precipitant solution to obtain a reaction system, followed by static growth at low temperature. Adjusting the ratio of the mixed solution of cobalt salt and aluminum salt to the precipitant solution effectively adjusts the type and morphology of the product. The prepared basic cobalt carbonate has a smaller particle size and is a nanocluster composed of stacked smaller flakes. At an optimal volume ratio, cobalt carbonate with a relatively perfect spherical morphology and a particle size concentrated between 7 and 8 μm can be obtained.

[0065] In general, the present invention does not introduce additional surfactants and complexing agent structure adjustment agents, but only mixes the mixed solution of aluminum salt and cobalt salt with the precipitant solution. By adjusting the ratio of the mixed solution of aluminum salt and cobalt salt to the precipitant solution, the type and morphology of the product can be effectively controlled. The present invention stops stirring after the mixed solution of aluminum salt and cobalt salt is stirred and mixed with the precipitant solution to obtain a reaction system, and allows the system to stand and heat up for growth, thereby avoiding problems such as poor crystal consistency caused by unstable continuous feeding of the metering pump; there are fewer reaction steps, and the requirements for personnel and equipment are low, which is conducive to stable product production. At the same time, the number of personnel operation steps and device stirring are reduced, reducing labor and electricity costs. The prepared aluminum-doped cobalt precursor has different configurations and morphologies and has very good application prospects.

[0066] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum-doped cobalt precursor, characterized in that: include, The mixed solution of the cobalt salt and the aluminum salt and the precipitant solution are stirred and then the stirring is stopped to obtain a reaction system; The reaction system is heated to allow the product to grow, and the aluminum-doped cobalt precursor is collected; The heating raises the temperature of the reaction system to 40-60°C; The growth time is 15-20h; The concentrations of cobalt salt and aluminum salt in the mixed solution of cobalt salt and aluminum salt are 90-150 g / L and 1.4-1.7 g / L respectively; The concentration of the precipitant in the precipitant solution is 200-260 g / L, and the precipitant includes at least one of a soluble carbonate and a soluble bicarbonate; The volume ratio of the mixed solution of the cobalt salt and the aluminum salt to the precipitant solution is 1:0.4-1.4; The stirring and mixing is continued for 1-2 hours at a rotation speed of 180-230 rpm.

2. The method for preparing an aluminum-doped cobalt precursor according to claim 1, wherein: Said collecting comprises washing and drying; The washing reduces the concentration of impurity ions in the washing liquid to less than 20 ppm; The drying is carried out at 100-130°C.

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