Aluminum-doped cobaltosic oxide and preparation method thereof

Abstract

The invention discloses aluminum-doped cobaltosic oxide and a preparation method thereof.The preparation method comprises the steps that a cobalt salt solution, an aluminum salt solution, a precipitant solution and a regulator solution are mixed for reaction, and insoluble substances are collected; carrying out heat treatment on the insoluble substance to obtain aluminum-doped cobaltosic oxide; wherein a regulator in the regulator solution comprises at least one of D-glucosamine sodium sulfate and sodium benzoate. In the process of preparing the aluminum-doped cobaltosic oxide by a precipitation method, the D-glucosamine sodium sulfate and the sodium benzoate are added, so that the microstructure of the aluminum-doped cobaltosic oxide is effectively adjusted, the structure is more uniform, and the dispersity is better. And meanwhile, D-glucosamine sodium sulfate and sodium benzoate in a certain concentration range are also beneficial to improving the tap density of the aluminum-doped cobaltosic oxide. On the whole, the preparation method is simple, raw materials are easy to obtain, and the preparation method has a good application prospect.

Description

Technical Field

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

[0002] The rapid development of electronic products has increased the market demand for large-capacity and high-rate lithium-ion batteries, and lithium cobalt oxide is developing towards a high voltage of more than 4.5V. Higher voltage will cause more lithium ions to escape from the crystal structure, seriously affecting the structural stability of the material, and further affecting the cycle performance and safety performance of the battery. Cobalt tetroxide is the main raw material of lithium cobalt oxide. Under the premise of increasing the capacity and cycle performance requirements of lithium cobalt oxide, more requirements are also put forward for cobalt tetroxide.

[0003] Aluminum-doped cobalt oxide crystals can be formed by aluminum doping, which improves the conductivity and stability of lithium cobalt oxide electrode materials, thereby improving the capacity and cycle life of the battery. Some studies have used liquid phase precipitation to prepare aluminum-doped cobalt tetroxide. For example, CN108373175A discloses aluminum-doped cobalt tetroxide and its preparation method and application, wherein a cobalt salt solution, a carbonate ion-containing precipitant solution and a mixed solution of an aluminum salt and a complexing agent are co-precipitated to prepare aluminum-doped cobalt carbonate, and then calcined to prepare aluminum-doped cobalt tetroxide. This method can successfully prepare aluminum-doped cobalt tetroxide with a relatively uniform particle size and a spherical shape. However, the feed rate of each raw material is slow, which makes the preparation cycle longer. CN114368792A discloses a method for preparing aluminum-doped cobalt tetroxide particles. A cobalt salt solution, an ammonium bicarbonate solution and a sodium aluminate solution are reacted to obtain cobalt carbonate, which is then calcined to prepare cobalt tetroxide. This method can prepare aluminum-doped cobalt tetroxide with a particle size of 14-17μm and good uniformity. However, there are a large number of pores on the surface of aluminum-doped cobalt tetroxide, which has the disadvantage of low tap density. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a method for preparing aluminum-doped cobalt oxide, comprising: Mixing a cobalt salt solution, an aluminum salt solution, a precipitant solution, and a regulator solution for reaction, and collecting insoluble matter; The insoluble matter is heat treated to obtain aluminum-doped cobalt tetroxide; Wherein, the regulator in the regulator solution includes at least one of D-glucosamine sulfate sodium salt and sodium benzoate.

[0005] Further, the regulator solution is a mixed solution of D-glucosamine sulfate sodium salt and sodium benzoate; Wherein, the concentration of D-glucosamine sulfate sodium salt is 0.02-0.05 mol / L; the concentration of sodium benzoate is 0.01-0.03 mol / L.

[0006] Further, the concentration of the cobalt salt in the cobalt salt solution is 110-150 g / L; The concentration of aluminum salt in the aluminum salt solution is 1.2-1.6 g / L; The concentration of the precipitant in the precipitant solution is 0.1-0.2 mol / L.

[0007] In the present invention, the types of cobalt salt, aluminum salt and precipitant need not be strictly limited. For example, the cobalt salt can be at least one of cobalt sulfate, cobalt chloride, cobalt nitrate, etc.; the aluminum salt can be at least one of aluminum nitrate, aluminum chloride, aluminum sulfate, sodium aluminate, etc.; the precipitant can be at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, potassium bicarbonate, sodium bicarbonate, ammonium bicarbonate, etc. The solvent of the cobalt salt solution, aluminum salt solution and precipitant solution does not need to be strictly limited, and is a general solvent, such as at least one of water, ethanol, acetone, etc., preferably water.

[0008] Furthermore, the cobalt salt solution, aluminum salt solution, precipitant solution and regulator solution are mixed in a parallel flow manner at an inflow rate of 80-240 L / h.

[0009] Further, the mixed reaction is carried out at a temperature of 60-100° C., a pH of 9-10, and a stirring speed of 200-400 rpm. During the mixed reaction, the reagent for adjusting the pH does not need to be strictly limited, and can be exemplarily sodium hydroxide, potassium hydroxide, or aqueous solutions thereof. If the pH is excessively adjusted, a small amount of inorganic acid or inorganic acid aqueous solution is added. This is a conventional operation and can be adjusted as needed.

[0010] Furthermore, during the mixed reaction, 15-30 m 3 Air is introduced at a flow rate of / h.

[0011] Furthermore, before collecting the insoluble matter, the method further includes observing the particle size of the intermediate obtained by the mixing reaction, and collecting the insoluble matter after the median particle size of the intermediate reaches the target value.

[0012] Furthermore, the heat treatment is continued at a temperature of 550-850° C. for 4-12 hours.

[0013] The present invention also provides aluminum-doped cobalt tetroxide, which is obtained by the above-mentioned preparation method.

[0014] The present invention also provides the application of the aluminum-doped cobalt tetroxide in lithium battery materials.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention adds D-glucosamine sulfate sodium salt and sodium benzoate during the process of preparing aluminum-doped cobalt tetroxide by precipitation method, effectively adjusting the microscopic morphology of aluminum-doped cobalt tetroxide, making the structure more uniform and the dispersibility better. At the same time, D-glucosamine sulfate sodium salt and sodium benzoate in a certain concentration range are also conducive to improving the tap density of aluminum-doped cobalt tetroxide. Overall, the preparation method of the present invention is simple, the raw materials are easy to obtain, and it has a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] Figure 1 A flow chart showing the preparation method of aluminum-doped cobalt tetroxide of the present invention is shown; Figure 2 The scanning electron microscope image of aluminum-doped cobalt tetroxide prepared in Example 1 is shown; Figure 3 The scanning electron microscope image of aluminum-doped cobalt tetroxide prepared in Example 2 is shown; Figure 4 The scanning electron microscope image of aluminum-doped cobalt tetroxide prepared in Example 3 is shown; Figure 5 The scanning electron microscope image of aluminum-doped cobalt tetroxide prepared in Comparative Example 3 is shown; Figure 6 The scanning electron microscope image of the cobalt tetroxide prepared in Comparative Example 4 is shown. DETAILED DESCRIPTION

[0018] 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.

[0019] 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.

[0020] Example 1 like Figure 1 As shown, a method for preparing aluminum-doped cobalt oxide comprises the following steps: S1, preparing a reaction solution: cobalt chloride and water are mixed into a 130 g / L cobalt chloride solution; aluminum chloride and water are mixed into a 1.5 g / L aluminum chloride solution; sodium hydroxide and water are mixed into a 0.15 mol / L sodium hydroxide solution; D-glucosamine sulfate sodium salt and water are mixed into a 0.03 mol / L D-glucosamine sulfate sodium salt solution; S2, precipitation reaction: cobalt chloride solution, aluminum chloride solution, sodium hydroxide solution, and D-glucosamine sulfate sodium salt solution were injected into the reactor at flow rates of 150 L / h, 120 L / h, 180 L / h, and 90 L / h, respectively. 3 / h, temperature 80°C, pH 9.5, stirring speed 350rpm, mixing reaction, sampling once every 2h during the process, observing the particle size of the intermediate, when the median particle size of the intermediate is about 15μm, stop passing the reaction solution, filter the mixed system in the reactor, and dry to obtain the insoluble matter; S3. Heat treatment: keep the insoluble matter at 650°C for 8 hours to obtain aluminum-doped cobalt tetroxide.

[0021] Example 2 A method for preparing aluminum-doped cobalt oxide, comprising the following steps: S1, prepare reaction solution: prepare 130g / L cobalt chloride solution by cobalt chloride and water; prepare 1.5g / L aluminum chloride solution by aluminum chloride and water; prepare 0.15mol / L sodium hydroxide solution by sodium hydroxide and water; prepare 0.03mol / L sodium benzoate solution by sodium benzoate and water; S2, precipitation reaction: cobalt chloride solution, aluminum chloride solution, sodium hydroxide solution, sodium benzoate solution were injected into the reactor at flow rates of 150 L / h, 120 L / h, 180 L / h, and 90 L / h respectively. 3 / h, temperature 80°C, pH 9.5, stirring speed 350rpm, mixing reaction, sampling once every 2h during the process, observing the particle size of the intermediate, when the median particle size of the intermediate is about 15μm, stop passing the reaction solution, filter the mixed system in the reactor, and dry to obtain the insoluble matter; S3. Heat treatment: keep the insoluble matter at 650°C for 8 hours to obtain aluminum-doped cobalt tetroxide.

[0022] Example 3 A method for preparing aluminum-doped cobalt oxide, comprising the following steps: S1, prepare reaction solution: prepare 130g / L cobalt chloride solution by cobalt chloride and water; prepare 1.5g / L aluminum chloride solution by aluminum chloride and water; prepare 0.15mol / L sodium hydroxide solution by sodium hydroxide and water; prepare 0.02mol / L D-glucosamine sulfate sodium salt and 0.01mol / L sodium benzoate mixed solution by D-glucosamine sulfate sodium salt, sodium benzoate and water; S2, precipitation reaction: cobalt chloride solution, aluminum chloride solution, sodium hydroxide solution, D-glucosamine sulfate sodium salt and sodium benzoate mixed solution were injected into the reactor at flow rates of 150 L / h, 120 L / h, 180 L / h and 90 L / h respectively. 3 / h, temperature 80°C, pH 9.5, stirring speed 350rpm, mixing reaction, sampling once every 2h during the process, observing the particle size of the intermediate, when the median particle size of the intermediate is about 15μm, stop passing the reaction solution, filter the mixed system in the reactor, and dry to obtain the insoluble matter; S3. Heat treatment: keep the insoluble matter at 650°C for 8 hours to obtain aluminum-doped cobalt tetroxide.

[0023] Example 4 A method for preparing aluminum-doped cobalt oxide is basically the same as that of Example 3, except that: in step S1, D-glucosamine sulfate sodium salt, sodium benzoate and water are prepared into a mixed solution of 0.03 mol / L D-glucosamine sulfate sodium salt and 0.02 mol / L sodium benzoate. Example 5 A method for preparing aluminum-doped cobalt oxide is basically the same as Example 3, except that: in step S1, D-glucosamine sodium sulfate, sodium benzoate and water are prepared into a mixed solution of 0.05 mol / L D-glucosamine sodium sulfate and 0.03 mol / L sodium benzoate.

[0024] Comparative Example 1 A method for preparing aluminum-doped cobalt oxide is basically the same as Example 3, except that: in step S1, D-glucosamine sodium sulfate, sodium benzoate and water are prepared into a mixed solution of 0.015 mol / L D-glucosamine sodium sulfate and 0.008 mol / L sodium benzoate.

[0025] Comparative Example 2 A method for preparing aluminum-doped cobalt oxide is basically the same as Example 3, except that: in step S1, D-glucosamine sodium sulfate, sodium benzoate and water are prepared into a mixed solution of 0.06 mol / L D-glucosamine sodium sulfate and 0.04 mol / L sodium benzoate.

[0026] Comparative Example 3 A method for preparing aluminum-doped cobalt oxide, comprising the following steps: S1, preparing a reaction solution: cobalt chloride and water are mixed into a 130 g / L cobalt chloride solution; aluminum chloride and water are mixed into a 1.5 g / L aluminum chloride solution; sodium hydroxide and water are mixed into a 0.15 mol / L sodium hydroxide solution; S2, precipitation reaction: cobalt chloride solution, aluminum chloride solution, sodium hydroxide solution, respectively, at 150L / h, 120L / h, 180L / h flow rate, injected into the reactor, under an air flow rate of 25m 3 / h, temperature 80°C, pH 9.5, stirring speed 350rpm, mixing reaction, sampling once every 2h during the process, observing the particle size of the intermediate, when the median particle size of the intermediate is about 15μm, stop passing the reaction solution, filter the mixed system in the reactor, and dry to obtain the insoluble matter; S3. Heat treatment: keep the insoluble matter at 650°C for 8 hours to obtain aluminum-doped cobalt tetroxide.

[0027] Comparative Example 4 A method for preparing cobalt tetroxide comprises the following steps: S1. Prepare a reaction solution: prepare a 130 g / L cobalt chloride solution by mixing cobalt chloride and water; prepare a 0.15 mol / L sodium hydroxide solution by mixing sodium hydroxide and water; S2, precipitation reaction: cobalt chloride solution and sodium hydroxide solution were injected into the reactor at a flow rate of 150L / h and 180L / h respectively. 3 / h, temperature 80°C, pH 9.5, stirring speed 350rpm, mixing reaction, sampling once every 2h during the process, observing the particle size of the intermediate, when the median particle size of the intermediate is about 15μm, stop passing the reaction solution, filter the mixed system in the reactor, and dry to obtain the insoluble matter; S3. Heat treatment: keep the insoluble matter at 650°C for 8 hours to obtain cobalt tetroxide.

[0028] Test Case The microscopic morphology of the materials prepared in Examples 1-3 of the present invention and Comparative Examples 3 and 4 was observed using a scanning electron microscope. The results are as follows: Figure 2-Figure 6As shown. Because the median particle size of the intermediate is controlled, the cobalt oxide materials prepared in these embodiments and comparative examples have similar particle sizes, and comparative example 4 without the introduction of aluminum has a more uniform, well-dispersed spherical structure; compared with comparative example 4, the aluminum-doped cobalt oxide in comparative example 3 is broken, and the aluminum element enters the reaction in the form of trivalent cations, while the cobalt element enters the reaction in the form of divalent cations. Since the precipitation rate of trivalent aluminum is higher than that of divalent cobalt, the distribution uniformity of the aluminum element is poor, and the distribution of aluminum in the intermediate is uneven, which leads to the collapse of the structure during calcination; the structures of Examples 1 and 2, which respectively introduce D-glucosamine sodium sulfate and sodium benzoate, are significantly improved compared to the structure of Comparative Example 3, because they can promote the dispersibility of aluminum in the intermediate and improve the stability of the intermediate. It is worth noting that Example 3, which adds D-glucosamine sodium sulfate and sodium benzoate, has good dispersibility, the crushing phenomenon has been significantly improved, and the structure is similar to Comparative Example 4. Examples 4, 5 and Comparative Examples 1, 2 have similar structures to Example 3 and are not described here. These results show that the introduction of D-glucosamine sulfate sodium salt and sodium benzoate during the precipitation reaction can improve the stability and dispersibility of aluminum-doped cobalt tetroxide.

[0029] The tap density of the cobalt oxide materials prepared in the examples and comparative examples was also tested, and the results are shown in Table 1.

[0030] Table 1 Tap density results

[0031] It can be seen from the test results in Table 1 that the present invention can effectively improve the tap density of the cobalt oxide material by introducing D-glucosamine sulfate sodium salt or sodium benzoate during the precipitation reaction. At the same time, when D-glucosamine sulfate sodium salt and sodium benzoate are introduced together, there is an optimal concentration, which can further improve the tap density.

[0032] 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 aluminum-doped cobalt oxide, characterized in that: include, Mixing a cobalt salt solution, an aluminum salt solution, a precipitant solution, and a regulator solution for reaction, and collecting insoluble matter; The insoluble matter is heat treated to obtain aluminum-doped cobalt tetroxide; Wherein, the regulator in the regulator solution includes at least one of D-glucosamine sulfate sodium salt and sodium benzoate.

2. The method for preparing aluminum-doped cobalt tetroxide according to claim 1, characterized in that: The regulator solution is a mixed solution of D-glucosamine sulfate sodium salt and sodium benzoate; Wherein, the concentration of D-glucosamine sulfate sodium salt is 0.02-0.05 mol / L; the concentration of sodium benzoate is 0.01-0.03 mol / L.

3. The method for preparing aluminum-doped cobalt tetroxide according to claim 1, characterized in that: The concentration of cobalt salt in the cobalt salt solution is 110-150 g / L; The concentration of aluminum salt in the aluminum salt solution is 1.2-1.6 g / L; The concentration of the precipitant in the precipitant solution is 0.1-0.2 mol / L.

4. The method for preparing aluminum-doped cobalt tetroxide according to claim 1, characterized in that: The cobalt salt solution, aluminum salt solution, precipitant solution and regulator solution are mixed in a parallel flow manner at an inflow rate of 80-240 L / h.

5. The method for preparing aluminum-doped cobalt tetroxide according to claim 1, characterized in that: The mixing reaction is carried out at a temperature of 60-100° C., a pH of 9-10, and a stirring speed of 200-400 rpm.

6. The method for preparing aluminum-doped cobalt tetroxide according to claim 5, characterized in that: During the mixed reaction, 15-30m 3 Air is introduced at a flow rate of / h.

7. The method for preparing aluminum-doped cobalt tetroxide according to claim 5, characterized in that: Before collecting the insoluble matter, the step of observing the particle size of the intermediate obtained by the mixing reaction is also included, and the insoluble matter is collected after the median particle size of the intermediate reaches the target value.

8. The method for preparing aluminum-doped cobalt tetroxide according to any one of claims 1 to 7, characterized in that: The heat treatment is continued at a temperature of 550-850° C. for 4-12 hours.

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

10. Use of the aluminum-doped cobalt tetroxide as claimed in claim 9 in lithium battery materials.

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