Aluminum-doped cobalt precursor and preparation method and application thereof

Abstract

The invention discloses an aluminum-doped cobalt precursor and a preparation method and application thereof.The preparation method comprises the steps that a mixed solution of cobalt salt and aluminum salt and a precipitant solution are stirred and mixed, then stirring is stopped, and a reaction system is obtained; and heating the reaction system to enable the product to grow, and collecting to obtain the aluminum-doped cobalt precursor. On the basis of not introducing additional surfactant and complexing agent structure adjusting auxiliaries, only the mixed solution of the aluminum salt and the cobalt salt is mixed with the precipitant solution, and the type and morphology of the product can be effectively regulated and controlled by adjusting the ratio of the mixed solution of the aluminum salt and the cobalt salt to the precipitant solution. According to the method, stirring is stopped when a reaction system is obtained after the mixed solution of the aluminum salt and the cobalt salt and the precipitant solution are stirred and mixed, and standing and heating growth are performed, so that the problems of poor crystal consistency and the like caused by unstable continuous feeding of a metering pump are solved; the reaction process is few, the requirements on personnel and equipment are lower, the stable production of products is facilitated, and meanwhile, the manpower and electric power cost is reduced.

Description

Technical Field

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

[0002] Cobalt carbonate and basic cobalt carbonate can be used not only as precursors for the production of battery materials such as cobalt trioxide and lithium cobaltate, but also as precursors for the preparation of catalysts. Whether as precursors for the production of battery materials or precursors of catalysts, these derivative products have a great inheritance of the performance of cobalt carbonate and basic cobalt carbonate. For example, the doping of aluminum in cobalt carbonate and basic cobalt carbonate can improve the stability of the derived lithium cobaltate positive electrode material. At the same time, the morphology and particle size of cobalt carbonate and basic cobalt carbonate also have a great influence on the discharge performance of the derived lithium cobaltate positive electrode material.

[0003] For this reason, researchers have done a lot of research on aluminum-doped cobalt carbonate and basic cobalt carbonate. CN118811868A discloses a method for preparing aluminum-doped basic cobalt carbonate material, firstly mixing cobalt salt, aluminum salt and non-ionic surfactant to prepare mixed solution 1, mixing ammonium bicarbonate solution and ammonia-ammonium chloride buffer solution to prepare mixed solution 2, then mixing mixed solution 1 with mixed solution 2, controlling pH, reacting under heating and stirring to obtain seed solution, then adding mixed solution 1 and mixed solution 2 to the seed solution, controlling pH, reacting under heating and stirring to obtain spherical aluminum-doped basic cobalt carbonate. This method uses non-ionic surfactant to complex cobalt ions, so that cobalt ions are slowly precipitated in an orderly manner, and ammonia-ammonium chloride buffer solution can effectively prevent pH mutation in the system, and prepare aluminum-doped basic cobalt carbonate with good sphericity. However, this method requires strict control of reaction pH, and the operation is relatively cumbersome. CN115477331A discloses an aluminum-doped cobalt carbonate and a preparation method thereof, wherein a soluble cobalt salt, a soluble aluminum salt and a dispersant are dissolved in water to obtain a metal liquid A, a soluble cobalt salt and a soluble aluminum salt are dissolved in water to obtain a metal liquid B, bicarbonate is prepared as a base liquid, and carbonate is prepared as a precipitant; the metal liquid A and the precipitant are added to the base liquid in parallel, reacted, and a mixed system containing aluminum-doped cobalt carbonate crystals is generated, and when the median particle size of the aluminum-doped cobalt carbonate crystals to be generated reaches 14-15 μm, the addition of the metal liquid A to the mixed system is stopped, and the metal liquid B and the precipitant are added to the mixed system in parallel, and the reaction obtains spherical aluminum-doped cobalt carbonate. This method can obtain cobalt carbonate with a median particle size of 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 purpose of the present invention is to prepare the desired aluminum-doped cobalt precursor by adjusting the ratio of the mixed solution of aluminum salt and cobalt salt to the precipitant solution without introducing additional surfactants and complexing agent structure adjustment agents, and growing at a lower temperature without stirring again after mixing.

[0006] In order to achieve the above object, the present invention provides a method for preparing an aluminum-doped cobalt precursor, comprising: The mixed solution of the cobalt salt and the aluminum salt and the precipitant solution are stirred and mixed, 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.

[0007] Further, the heating raises the temperature of the reaction system to 40-60°C; The growth time is 15-20 hours.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] Furthermore, the stirring and mixing is continued for 1-2 hours at a rotation speed of 180-230 rpm.

[0012] Further, the collecting includes 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.

[0013] It should be noted that the present invention does not need to 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, cobalt nitrate hexahydrate, etc.; the aluminum salt can be at least one of aluminum nitrate nonahydrate, anhydrous aluminum chloride, aluminum sulfate 18hydrate, etc. The precipitant can be at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium bicarbonate, etc. The solvent for the mixed solution of the cobalt salt and the aluminum salt and the precipitant solution does not need to be strictly limited. For example, it can be at least one of water, ethanol, acetone, etc., preferably water.

[0014] The present invention also provides an aluminum-doped cobalt precursor, which is obtained by the above method.

[0015] Furthermore, the morphology of the aluminum-doped cobalt precursor is nanosheet clusters or spherical shapes.

[0016] The present invention also provides the use of the aluminum-doped cobalt precursor as a precursor of battery materials and catalysts.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 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.

[0018] 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 left to stand and heated for growth, thereby avoiding the problems of poor crystal consistency caused by unstable continuous feeding of a metering pump; the number of reaction processes is small, the requirements on personnel and equipment are low, and the stable production of products is facilitated; meanwhile, the number of operating steps for personnel and stirring of equipment is reduced, thereby reducing the labor and electricity costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0020] Figure 1 A flow chart showing a method for preparing an aluminum-doped cobalt precursor according to Example 1; Figure 2 The XRD patterns of the aluminum-doped cobalt precursors prepared in Examples 1 to 10 are shown; Figure 3 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 1; Figure 4 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 2; Figure 5 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 3; Figure 6 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 4; Figure 7 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 5; Figure 8 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 6; Fig. 9 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 7; Fig.10 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 8; Fig.11 shows a scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 9; Fig.12 A scanning electron microscope image of the aluminum-doped cobalt precursor prepared in Example 10 is shown. DETAILED DESCRIPTION

[0021] The endpoints and any values ​​of the ranges disclosed in the present invention 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 endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0022] The following will be combined with the specific embodiments of the present invention and the drawings of the specification to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0023] Example 1 like Figure 1 As shown, a method for preparing an aluminum-doped cobalt precursor comprises the following steps: S1. Dissolve 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; dissolve ammonium bicarbonate in water to prepare a precipitant solution with an ammonium bicarbonate concentration of 230 g / L; S2, stirring 1000 L of the mixed solution of cobalt salt and 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; S3. The reaction system is heated to 42°C and allowed to stand for 20 hours to allow the product to grow. The slurry is filtered and then filtered and washed with water until the concentration of chloride ions and sodium ions in the water is less than 20 ppm. The insoluble matter is transferred to 120°C for drying to obtain an aluminum-doped cobalt precursor.

[0024] Example 2-Example 10 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.

[0025] Table 1 Volume ratio of the mixed solution of cobalt salt and aluminum salt and the precipitant solution in the embodiment

[0026] Embodiment 11 The method is basically the same as Example 1, except that cobalt nitrate hexahydrate is used instead of cobalt chloride hexahydrate in step S1.

[0027] Example 12 The method is basically the same as Example 1, except that aluminum nitrate nonahydrate is used in step S1 instead of anhydrous aluminum chloride.

[0028] Example 13 The method is basically the same as Example 1, except that sodium bicarbonate is used instead of ammonium bicarbonate in step S1.

[0029] Embodiment 14 The method is basically the same as Example 1, except that cobalt nitrate hexahydrate is used instead of cobalt chloride hexahydrate in step S1.

[0030] Embodiment 15 The method is basically the same as Example 1, except that aluminum nitrate nonahydrate is used in step S1 instead of anhydrous aluminum chloride.

[0031] Example 16 The method is basically the same as Example 1, except that sodium bicarbonate is used instead of ammonium bicarbonate in step S1.

[0032] Test Case The crystal structures of the aluminum-doped cobalt precursors prepared in Examples 1-10 were tested by 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 value 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.

[0033] The morphology of the aluminum-doped cobalt precursors prepared in Examples 1-10 was further tested using a scanning electron microscope, and 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 carbonate prepared in Examples 6 to 10 is 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. Fig. 9) has the most regular shape, with less surface agglomeration. The amount of ammonium bicarbonate solution in Examples 8-10 is larger, and a large number of spherical cobalt carbonates have small cobalt carbonate particles attached to the surface.

[0034] These results illustrate that the present invention successfully obtains a reaction system by stirring a mixed solution of cobalt salt and aluminum salt with a precipitant solution and then allowing the mixture to grow at low temperature. By adjusting the ratio of the mixed solution of cobalt salt and aluminum salt to the precipitant solution, the type and morphology of the product can be effectively adjusted. The prepared basic cobalt carbonate has a smaller particle size and is a nanocluster formed by stacking smaller sheets. At a preferred volume ratio, cobalt carbonate with a relatively perfect spherical morphology and a particle size concentrated in the range of 7-8 μm can be obtained.

[0035] In general, the present invention does not introduce additional surfactants and complexing agent structure adjustment agents, 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. After the aluminum salt and cobalt salt mixed solution and the precipitant solution are stirred and mixed to obtain a reaction system, stirring is stopped, and the system is left 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 processes, and the requirements for personnel and equipment are relatively low, which is conducive to stable production of products. At the same time, the number of personnel operation steps and device stirring are reduced, which reduces labor and electricity costs. The prepared aluminum-doped cobalt precursor has different configurations and morphologies and has very good application prospects.

[0036] 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, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to 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 protection scope 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 mixed, 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.

2. The method for preparing an aluminum-doped cobalt precursor according to claim 1, characterized in that: The heating raises the temperature of the reaction system to 40-60°C; The growth time is 15-20 hours.

3. The method for preparing an aluminum-doped cobalt precursor according to claim 1, characterized in that: 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.

4. The method for preparing an aluminum-doped cobalt precursor according to claim 1, characterized in that: 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.

5. The method for preparing an aluminum-doped cobalt precursor according to claim 1, characterized in that: 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.

6. The method for preparing an aluminum-doped cobalt precursor according to claim 1, characterized in that: The stirring and mixing is continued for 1-2 hours at a rotation speed of 180-230 rpm.

7. The method for preparing an aluminum-doped cobalt precursor according to claim 1, characterized in that: 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.

8. An aluminum-doped cobalt precursor, characterized in that: The method is obtained by the method according to any one of claims 1 to 7.

9. The aluminum-doped cobalt precursor according to claim 8, characterized in that: Its morphology is nanosheet clusters or spherical.

10. Use of the aluminum-doped cobalt precursor according to claim 8 as a precursor of battery materials and catalysts.

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