Alkali cobalt carbonate with high aluminum doping amount and preparation method thereof

Abstract

The invention relates to high-aluminum-content basic cobalt carbonate and a preparation method thereof. The method comprises the following steps: 1) preparing a mixed solution from cobalt salt and aluminum salt; (2) adding a small amount of ammonium bicarbonate solution into a reaction kettle, starting heating, adding the mixed solution into the reaction kettle while stirring, controlling the pH value, and reacting to obtain a seed crystal dispersion liquid; and (3) adding the mixed solution and an ammonium bicarbonate solution into the seed crystal dispersion liquid, controlling the pH value, continuously reacting under heating and stirring until the particle size of the basic cobalt carbonate reaches a set value, stopping the reaction, and carrying out filter pressing, washing and drying to obtain the basic cobalt carbonate with high aluminum doping amount. The aluminum doping in the basic cobalt carbonate provided by the invention is as high as 7767-8357ppm, and the aluminum element is uniformly distributed and does not segregate.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery positive electrode material preparation, and in particular to a high-aluminum-doped basic cobalt carbonate and a preparation method thereof. Background Art

[0002] With the rapid development of renewable energy, battery technology has become a hot topic in research. Lithium-ion batteries and hydrogen fuel cells are widely used in electric vehicles and energy storage systems. However, existing battery materials still have certain limitations in terms of conductivity, cycle stability and energy density.

[0003] Lithium cobalt oxide positive electrode material is one of the key materials for making lithium batteries, and cobalt carbonate is an important upstream material for producing lithium cobalt oxide positive electrode material. The performance of cobalt carbonate directly affects the final performance of lithium cobalt oxide products.

[0004] Aluminum doping can improve the conductivity and structural stability of cobalt carbonate, thereby improving the overall performance of the battery. However, most of the existing technologies have the problem of small aluminum doping amount, uneven distribution of aluminum elements and easy segregation, which is not conducive to improving the structural stability of cobalt carbonate. Summary of the invention

[0005] In view of the above problems, a high aluminum-doped basic cobalt carbonate and a preparation method thereof are now provided, aiming to provide a high aluminum-doped basic cobalt carbonate with uniform aluminum distribution and no segregation, thereby improving the structural stability of the cobalt carbonate.

[0006] The specific technical solutions are as follows:

[0007] The first aspect of the present invention is to provide a method for preparing basic cobalt carbonate with a high aluminum content, comprising:

[0008] 1) Prepare a mixed solution using cobalt salt and aluminum salt;

[0009] 2) adding a small amount of ammonium bicarbonate solution into the reaction kettle, turning on the heating, adding the mixed solution into the reaction kettle under stirring, controlling the pH, and reacting to obtain a seed crystal dispersion;

[0010] 3) adding the mixed solution and the ammonium bicarbonate solution to the seed crystal dispersion, controlling the pH, continuing the reaction under heating and stirring until the particle size of the basic cobalt carbonate reaches a set value, stopping the reaction, filtering, washing, and drying to obtain a basic cobalt carbonate with a high aluminum content.

[0011] Furthermore, in step 1), the concentration of cobalt ions in the mixed solution is 110-130 g / L, and the mass ratio of aluminum element to cobalt element is (0.015-0.017):1.

[0012] Furthermore, the cobalt salt is one or more of cobalt chloride, cobalt sulfate and cobalt nitrate.

[0013] Furthermore, the aluminum salt is one or more of aluminum chloride, aluminum sulfate, and aluminum nitrate.

[0014] Furthermore, in step 2) and step 3), the concentration of the ammonium bicarbonate solution is 220-240 g / L.

[0015] Furthermore, in step 3), the pH is controlled by adjusting the flow rates of the mixed solution and the ammonium bicarbonate solution, the flow rate of the mixed solution 1 is 1.61-1.76 kg / h, and the flow rate of the ammonium bicarbonate solution is 3.12-3.33 kg / h.

[0016] Furthermore, in step 2) and step 3), the pH value is 7.2-7.3.

[0017] Furthermore, the heating temperature in step 2) and step 3) is 40-43°C.

[0018] Furthermore, in step 3), the reaction is stopped when the particle size is 5-8 um.

[0019] The second aspect of the present invention is to provide a high aluminum-doped basic cobalt carbonate, which is prepared according to the above preparation method, and the aluminum doping amount of the high aluminum-doped basic cobalt carbonate is 7767-8357ppm.

[0020] The beneficial effects of the above scheme are:

[0021] 1) In the present invention, a high-aluminum-doped basic cobalt carbonate is prepared by optimizing the preparation parameters. Compared with the prior art, the aluminum doping in the basic cobalt carbonate is as high as 7767-8357 ppm, which increases the aluminum content embedded in the cobalt oxide lattice, effectively improves the stability of the structure, can effectively improve the charge and discharge cycle performance of the battery, and prolong the battery life;

[0022] 2) The aluminum element in the basic cobalt carbonate provided by the present invention is evenly distributed without segregation;

[0023] 3) The preparation method provided by the present invention is simple and easy to implement, and is worthy of wide promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a SEM image of the high aluminum-doped basic cobalt carbonate provided in Example 1 of the present invention;

[0025] Figure 2 This is the XRD diagram of the aluminum-doped basic cobalt carbonate provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention 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.

[0027] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0029] Example 1

[0030] 1) preparing a mixed solution using cobalt chloride and aluminum nitrate, wherein the cobalt ion concentration in the mixed solution is 110 g / L, and the mass ratio of aluminum element to cobalt element is 0.015:1;

[0031] 2) Add a small amount of 220 g / L ammonium bicarbonate solution into the reactor, heat to 40-43° C., add the mixed solution into the reactor at a stirring speed of 450-500 rpm, control the pH to 7.2±0.1, and react to obtain a seed dispersion;

[0032] 3) adding the mixed solution and the ammonium bicarbonate solution (with a concentration of 220 g / L) to the seed crystal dispersion, controlling the pH to 7.2±0.1 (the pH is controlled by adjusting the flow rates of the mixed solution and the ammonium bicarbonate solution, the flow rate of the mixed solution 1 is 1.76 kg / h, and the flow rate of the ammonium bicarbonate solution is 3.12 kg / h), continuing the reaction at a constant heating temperature and stirring rate until the particle size of the basic cobalt carbonate is 5.1 um, stopping the reaction, filtering, washing, and drying to obtain a basic cobalt carbonate with a high aluminum content.

[0033] like Figure 1 As shown, the basic cobalt carbonate provided in this embodiment is in the form of spherical particles aggregated from nanosheets, with high sphericity and good consistency, which indicates that there is a problem of no aluminum segregation in the basic cobalt carbonate.

[0034] like Figure 2 As shown, XRD shows that this embodiment provides a single pure phase of basic cobalt carbonate.

[0035] The aluminum content test shows that the aluminum content in the high aluminum-doped basic cobalt carbonate provided in this embodiment is 7767 ppm.

[0036] Example 2

[0037] 1) preparing a mixed solution using cobalt chloride and aluminum nitrate, wherein the cobalt ion concentration in the mixed solution is 121 g / L, and the mass ratio of aluminum element to cobalt element is 0.016:1;

[0038] 2) Add a small amount of 230 g / L ammonium bicarbonate solution into the reactor, heat to 40-43° C., add the mixed solution into the reactor at a stirring speed of 450-500 rpm, control the pH to 7.2±0.1, and react to obtain a seed dispersion;

[0039] 3) adding the mixed solution and the ammonium bicarbonate solution (with a concentration of 230 g / L) to the seed crystal dispersion, controlling the pH to 7.2±0.1 (the pH is controlled by adjusting the flow rates of the mixed solution and the ammonium bicarbonate solution, the flow rate of the mixed solution 1 is 1.69 kg / h, and the flow rate of the ammonium bicarbonate solution is 3.21 kg / h), continuing the reaction at a constant heating temperature and stirring rate until the particle size of the basic cobalt carbonate is 5-8 um, stopping the reaction, filtering, washing, and drying to obtain a basic cobalt carbonate with a high aluminum content.

[0040] The aluminum content test shows that the aluminum content in the high aluminum-doped basic cobalt carbonate provided in this embodiment is 8154 ppm.

[0041] Example 3

[0042] 1) preparing a mixed solution using cobalt chloride and aluminum nitrate, wherein the cobalt ion concentration in the mixed solution is 130 g / L, and the mass ratio of aluminum element to cobalt element is 0.017:1;

[0043] 2) Add a small amount of 240 g / L ammonium bicarbonate solution into the reactor, heat to 40-43° C., add the mixed solution into the reactor at a stirring speed of 450-500 rpm, control the pH to 7.3±0.1, and react to obtain a seed dispersion;

[0044] 3) adding the mixed solution and the ammonium bicarbonate solution (with a concentration of 240 g / L) to the seed crystal dispersion, controlling the pH to 7.3±0.1 (the pH is controlled by adjusting the flow rates of the mixed solution and the ammonium bicarbonate solution, the flow rate of the mixed solution 1 is 1.61 kg / h, and the flow rate of the ammonium bicarbonate solution is 3.33 kg / h), continuing the reaction at a constant heating temperature and stirring rate until the particle size of the basic cobalt carbonate is 5-8 um, stopping the reaction, filtering, washing, and drying to obtain a basic cobalt carbonate with a high aluminum content.

[0045] The aluminum content test shows that the aluminum content in the high aluminum-doped basic cobalt carbonate provided in this embodiment is 8357 ppm.

[0046] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing high-aluminum-doped basic cobalt carbonate, characterized in that: include: 1) Prepare a mixed solution using cobalt salt and aluminum salt; 2) adding a small amount of ammonium bicarbonate solution into the reaction kettle, turning on the heating, adding the mixed solution into the reaction kettle under stirring, controlling the pH, and reacting to obtain a seed crystal dispersion; 3) adding the mixed solution and the ammonium bicarbonate solution to the seed crystal dispersion, controlling the pH, continuing the reaction under heating and stirring until the particle size of the basic cobalt carbonate reaches a set value, stopping the reaction, filtering, washing, and drying to obtain a basic cobalt carbonate with a high aluminum content.

2. The method for preparing high aluminum-doped basic cobalt carbonate according to claim 1, characterized in that: Step 1) The cobalt ion concentration in the mixed solution is 110-130 g / L, and the mass ratio of aluminum element to cobalt element is (0.015-0.017):

1.

3. The method for preparing high aluminum-doped basic cobalt carbonate according to claim 2, characterized in that: The cobalt salt is one or more of cobalt chloride, cobalt sulfate and cobalt nitrate.

4. The method for preparing high aluminum-doped basic cobalt carbonate according to claim 2, characterized in that: The aluminum salt is one or more of aluminum chloride, aluminum sulfate and aluminum nitrate.

5. The method for preparing high aluminum-doped basic cobalt carbonate according to claim 1, characterized in that: The concentration of the ammonium bicarbonate solution in step 2) and step 3) is 220-240 g / L.

6. The method for preparing high aluminum-doped basic cobalt carbonate according to claim 1, characterized in that: In step 3), the pH is controlled by adjusting the flow rates of the mixed solution and the ammonium bicarbonate solution, wherein the flow rate of the mixed solution 1 is 1.61-1.76 kg / h, and the flow rate of the ammonium bicarbonate solution is 3.12-3.33 kg / h.

7. The method for preparing high aluminum-doped basic cobalt carbonate according to claim 1, characterized in that: In step 2) and step 3), the pH is 7.2-7.

3.

8. The method for preparing high aluminum-doped basic cobalt carbonate according to claim 1, characterized in that: The heating temperature in step 2) and step 3) is 40-43°C.

9. The method for preparing high aluminum-doped basic cobalt carbonate according to claim 1, characterized in that: In step 3), the reaction is stopped when the particle size is 5-8 um.

10. A high aluminum-doped basic cobalt carbonate, characterized in that: The high aluminum-doped basic cobalt carbonate is prepared by the preparation method according to any one of claims 1 to 9, wherein the aluminum doping amount of the high aluminum-doped basic cobalt carbonate is 7767-8357 ppm.

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