FR3139816A1 - COBALT CARBONATE PRECURSOR CO-DOPED WITH ALUMINUM AND NICKEL, ITS PREPARATION METHOD AND ITS USE - Google Patents

Abstract

A cobalt carbonate precursor co-doped with aluminum and nickel, its preparation method and its use, which belong to the technical field of lithium ion batteries, are provided. A spherical seed crystal of cobalt carbonate with good Al doping uniformity is prepared by using cobalt salt solution, aluminum salt solution and high concentration ammonium bicarbonate solution. Then, cobalt salt solution, nickel salt solution, aluminum salt solution and low concentration ammonium bicarbonate solution are added to prepare co-doped cobalt carbonate precursor. aluminum and nickel flakes. The preparation method can reduce the risk of low capacity caused by simply increasing the Al content, reduce the risk of nucleation in the middle and later stages of the synthesis process, improve the product yield, and improve the distribution uniformity of aluminum and nickel elements in the cobalt carbonate precursor co-doped with aluminum and nickel. [FIG. 1])

Description

COBALT CARBONATE PRECURSOR CO-DOPED WITH ALUMINUM AND NICKEL, ITS PREPARATION METHOD AND ITS USE

The embodiments of the present application relate to the technical field of lithium-ion batteries, for example a cobalt carbonate precursor co-doped with aluminum and nickel, its preparation method and its use.

BACKGROUND

Lithium cobaltate cathode material has high energy density and is mainly used in the field of computers, communications and consumer electronics (3C). With the popularization of 5G mobile phones, the capacity requirements of lithium-ion batteries are constantly increasing. Research shows that battery capacity can be effectively improved by increasing the charging cut-off voltage. For example, when the voltage increases from 4.45 V to 4.48 V, the energy density of a corresponding LCO battery can be increased by about 3.5%. However, increasing the voltage causes the crystal structure of the material to collapse, leading to rapid capacitance degradation.

Doping of elements can effectively solve the stability problem of the crystal structure of the material, for example, the cycling performance of lithium cobaltate at high voltages can be effectively improved by doping of elements such as Al, Mg, Ni, Mn , etc. Lithium cobaltate cathode material is mainly generated by sintering a mixture of tricobalt tetroxide and lithium carbonate, where tricobalt tetroxide is mainly generated by the thermal decomposition of cobalt carbonate on the market. From cobalt carbonate precursor to preoxidized tricobalt tetroxide to lithium cobaltate cathode material, some physical and chemical properties are inherited to a certain extent. The electrochemical performance of lithium cobaltate cathode material is greatly affected by the quality of cobalt carbonate.

Currently, the requirements for high-voltage cobalt carbonate precursors in the market are mainly: increasing the amount of Al doping and improving the uniformity of Al. In the process of preparing doped cobalt carbonate by liquid phase precipitation process, the following problems exist: the amount of doped aluminum is high and aluminum is an inactive element, resulting in capacity loss; Due to the large difference in the solubility product of each type of doped ions and cobalt ions, the precipitation of ions is not synchronous and the distribution of elements is not uniform. Therefore, it is difficult to simultaneously improve the amount of Al doping and the uniformity of Al.

SUMMARY

The following is the summary of the topic described in detail here. This summary is not intended to limit the scope of the claims.

The embodiments of the present application provide a cobalt carbonate precursor co-doped with aluminum and nickel, its preparation method and its use. Aluminum and nickel are uniformly doped in the aluminum and nickel co-doped cobalt carbonate precursor prepared by the process, thereby reducing the risk of low capacity caused by simply increasing the Al content, reducing thus reducing the risk of nucleation in the later stage of the synthesis process and improving the product yield.

The technical solution adopted by the embodiments of the present application is a process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel, comprising the following steps:

preparation of the solution: the preparation of a cobalt salt solution, a nickel salt solution, an aluminum salt solution, a high concentration ammonium bicarbonate solution, a low concentration ammonium bicarbonate solution and a base ammonium bicarbonate solution, respectively; where the concentration of cobalt ions in the cobalt salt solution is 100 to 130 g/L, the concentration of nickel ions in the nickel salt solution is 1 to 10 g/L, the concentration of nickel ions aluminum in aluminum salt solution is 5 to 15 g/L, the concentration of ammonium bicarbonate in high concentration ammonium bicarbonate solution is 220 to 240 g/L, the concentration of bicarbonate d ammonium in the low concentration ammonium bicarbonate solution is 120 to 180 g/L, and the concentration of ammonium bicarbonate in the basic ammonium bicarbonate solution is 40 to 120 g/L;

preparation of cobalt carbonate seed crystal: adding the ammonium bicarbonate base solution to a reaction vessel, adding the cobalt salt solution, the aluminum salt solution and the high concentration ammonium bicarbonate solution in parallel flow with heating and stirring, and the reaction to generate a cobalt carbonate seed crystal; And

preparation of cobalt carbonate precursor co-doped with aluminum and nickel: then adding the cobalt salt solution, the nickel salt solution, the aluminum salt solution and the solution of ammonium bicarbonate at low concentration to the seed crystal of cobalt carbonate in the reaction vessel in parallel flow with heating and stirring; filtering the material obtained from the reaction, and washing, drying and grinding the filtered material obtained to obtain a cobalt carbonate precursor co-doped with aluminum and nickel.

In the present application, a spherical seed crystal of cobalt carbonate with good Al doping uniformity is prepared by using a cobalt salt solution, an aluminum salt solution and a high concentration ammonium bicarbonate solution. . Then, a cobalt salt solution, a nickel salt solution, an aluminum salt solution and a low concentration ammonium bicarbonate solution are added to prepare a co-doped cobalt carbonate precursor. aluminum and nickel flakes. In the process of preparing cobalt carbonate seed crystal, the high concentration ammonium bicarbonate solution reacts with the cobalt salt solution and can also serve as a pH buffering agent so that the pH change of the system reaction is regulated within a small range. The resulting cobalt carbonate seed crystal has a high tap density and good Al uniformity. In the preparation process of cobalt carbonate precursor co-doped with aluminum and nickel, the low concentration ammonium bicarbonate solution provides sufficient carbonate ions for precipitation, and also helps to avoid precipitation. incomplete nickel caused by the fact that the solubility product of nickel carbonate is much higher than the solubility product of cobalt carbonate and aluminum hydroxide when nickel-cobalt-aluminum co-precipitation is carried out in a system of ammonium bicarbonate at high concentration, thus avoiding the loss of nickel in the supernatant. The resulting aluminum-nickel co-doped cobalt carbonate precursor exhibits a flake morphology to provide more growth sites for nickel co-precipitation, thereby reducing nickel loss. Such a structure has high porosity and good sintering activity to provide pathways for the diffusion of nickel in the preparation process of tricobalt tetroxide, thereby improving the distribution uniformity of nickel and improving the performance of tricobalt tetroxide.

Preferably, the aluminum salt solution comprises a complexing agent, and the molar ratio of the complexing agent to aluminum is (0.5 to 1):10; preferably, the complexing agent is at least one of disodium ethylenediaminetetraacetic acid, ammonium citrate, citric acid, tartaric acid or sulfosalicylic acid.

In the present application, a complexing agent is added to the aluminum salt solution, the complexing agent and the aluminum salt are complexed, and when the cobalt carbonate precursor co-doped with aluminum and nickel is prepared, the aluminum salt can be co-precipitated with cobalt and nickel at a relatively low precipitation rate in the reaction system without segregation of aluminum. After the complexing agent enters the reaction system, the aluminum ions are released and the aluminum ions undergo a precipitation reaction. After decomplexation, the complexing agent is evacuated with the concentration of the stock solution and does not complex with cobalt ions and nickel ions in the reaction system, thus avoiding the loss of cobalt and nickel.

Preferably, in the preparation of cobalt carbonate seed crystal, heating is carried out at a temperature of 38 to 45°C.

Preferably, in the preparation of cobalt carbonate seed crystal, the pH of a base solution is 8 to 9, the pH of a reaction solution is regulated to be between 7.5 and 8.0 in the feeding process, and the flow rate of cobalt salt solution per hour is 1% to 10% of the volume of the reaction vessel.

In the present application, the seed crystal of weakly structured cobalt carbonate is prepared by limiting factors such as the temperature of the reaction system, the pH of the reaction system and the rotation speed of the reaction system in the reaction solution. If the pH is below 7, the cobalt carbonate seed crystal cannot form easily. If the pH is greater than 8, the structure of the cobalt carbonate seed crystal formed is compact, the distribution of Al is not uniform and when the cobalt carbonate precursor co-doped with aluminum and nickel is prepared, the permeability of the doped elements on the cobalt carbonate seed crystal is low, which affects the doping effect of the doped elements. When the temperature of the reaction system is lower than 38°C, the number of precipitated particles is large, the particle size is small. When the reaction temperature is above 45°C, the number of precipitated particles is small and the particle size is large.

Preferably, in the preparation of cobalt carbonate precursor co-doped with aluminum and nickel, heating is carried out at a temperature of 45 to 55°C.

Preferably, in the preparation of cobalt carbonate precursor co-doped with aluminum and nickel, the pH of a reaction solution is regulated to be between 7.0 and 7.5 in the feeding process , and the flow rate of the cobalt salt solution per hour represents 1% to 10% of the volume of the reaction vessel.

In the present application, the cobalt carbonate precursor co-doped with aluminum and nickel with a flake structure is prepared by limiting factors such as reaction system temperature, reaction system pH and rotation speed. of the reaction system in the reaction solution. Cobalt salt solution, nickel salt solution, aluminum salt solution and ammonium bicarbonate solution at low concentration are applied to the cobalt carbonate seed crystal by co-precipitation to increase the size particles of the cobalt carbonate seed crystal so as to obtain the cobalt carbonate precursor co-doped with aluminum and nickel with a flake structure. When the temperature of the reaction system is lower than 45°C or the pH of the reaction system is higher than 7.5, the flake structure cannot form. When the reaction temperature is higher than 55°C or the pH of the reaction system is lower than 7.0, the number of precipitate particles obtained is small, the particle size is large, and the product yield is low.

In the present application, the cobalt carbonate seed crystal with different morphologies and the cobalt carbonate precursors co-doped with aluminum and nickel with different morphologies are obtained by adjusting the reaction temperature and pH of the reaction system to prepare the cobalt carbonate seed crystal and the reaction temperature and pH of the reaction system to prepare the cobalt carbonate precursor co-doped with aluminum and nickel. The preparation temperature of the cobalt carbonate seed crystal is lower than the preparation temperature of the cobalt carbonate precursor co-doped with aluminum and nickel, and the preparation pH of the cobalt carbonate seed crystal is higher than the pH of preparation of the cobalt carbonate precursor co-doped with aluminum and nickel. Preferably, the absolute value between the preparation temperature of the cobalt carbonate seed crystal and the preparation temperature of the cobalt carbonate precursor co-doped with aluminum and nickel is greater than 3°C, and the absolute value between the pH for preparing the cobalt carbonate seed crystal and the pH for preparing the cobalt carbonate precursor co-doped with aluminum and nickel is greater than 4°C.

Preferably, the cobalt salt is at least one of cobalt chloride, cobalt sulfate or cobalt nitrate.

Preferably, the nickel salt is at least one of nickel sulfate or nickel chloride.

Preferably, the aluminum salt is at least one of aluminum chloride or aluminum sulfate.

Preferably, the D ₅₀ of the cobalt carbonate seed crystal is 7 to 13 µm. If the D ₅₀ of cobalt carbonate seed crystal is too large, nickel ions cannot easily penetrate inside the seed crystal during the growth process, resulting in uniform distribution of elements of cobalt carbonate precursor and a reduction in the electrochemical performance of the cathode material.

Preferably, the D₅₀of the material obtained from the reaction is 15 to 20 µm. If the D₅₀of material obtained from the reaction is too large, the improvement of the circulation flow capacity of the material is hindered. If the D₅₀of the material obtained from the reaction is too small, the protective effect on the material is not obvious, and the number of nickel active sites is small, which increases the loss of nickel.

Preferably, a solvent used during washing is pure water or ammonium bicarbonate solution.

In the washing process, impurities on the surface of the obtained filtered material can be removed using pure water or ammonium bicarbonate solution. Preferably, the washing solvent is ammonium bicarbonate solution, and the concentration of the ammonium bicarbonate solution is 10 to 50 g/L. By using ammonium bicarbonate solution having a concentration of 10 to 50 g/L for washing, the introduction of other impurities can be avoided, thereby reducing the influence of impurities on the carbonate precursor of cobalt. The solute of the washing solvent is the same as the solute of the precipitant used to prepare the cobalt carbonate precursor, thereby improving the stability of the cobalt carbonate precursor and improving the electrochemical performance and stability of the cathode material.

The washing temperature of the filtered material obtained in the present application is a conventional washing temperature, and those skilled in the art can select an appropriate temperature according to actual needs. Preferably, the washing temperature is 25 to 80°C. When the filtered material is washed in the above temperature range, the surface of the filtered material can be further cleaned, thereby improving the purity of the cobalt carbonate precursor and improving the electrochemical performance of the cathode material.

In a second aspect, the embodiments of the present application provide a cobalt carbonate precursor co-doped with aluminum and nickel prepared by the process of preparing a cobalt carbonate precursor co-doped with aluminum and nickel. aluminum and nickel.

In a third aspect, the embodiments of the present application provide a tricobalt tetroxide prepared by calcination of the cobalt carbonate precursor co-doped with aluminum and nickel.

The preparation process for tricobalt tetroxide in the present application is a conventional calcination process which can be one-step calcination or two-step calcination, and those skilled in the art can select a suitable process according to actual needs. The temperature and duration of the calcination can also be adjusted according to the calcination method of the related art, for example, the one-step calcination step consists of carrying out the calcination at a temperature of 500 to 700°C for 2 .5 to 6.5 hours. The steps of the two-step calcination are as follows: the calcination is carried out at a temperature of 250 to 350°C for 2 to 4 h, then the temperature is increased and the calcination is then carried out at a temperature of 500 to 700° C for 2 to 4 hours.

Due to the difference between the internal and external concentrations of nickel elements in the cobalt carbonate precursor co-doped with aluminum and nickel, the external nickel elements migrate inward along the flake structure with high porosity and good sintering activity in the calcination process, thereby further improving the distribution uniformity of doped elements in tricobalt tetroxide and improving the performance of tricobalt tetroxide.

In the calcination process, the cobalt carbonate precursor co-doped with aluminum and nickel is calcined in an air atmosphere or an oxygen atmosphere. The oxygen atmosphere preferably has an oxygen concentration of, for example, 10 volume percent and above and 50 volume percent and less.

Compared to the related art, the present application has the beneficial effects described below. In the present application, a spherical seed crystal of cobalt carbonate with good Al doping uniformity is prepared by using a cobalt salt solution, an aluminum salt solution and a high concentration ammonium bicarbonate solution. . Then, cobalt salt solution, nickel salt solution, aluminum salt solution and low concentration ammonium bicarbonate solution are added to prepare co-doped cobalt carbonate precursor. aluminum and nickel flakes. In the process of preparing cobalt carbonate seed crystal, the high concentration ammonium bicarbonate solution reacts with the cobalt salt solution and can also serve as a pH buffering agent so that the pH change of the system reaction is regulated within a small range. The resulting cobalt carbonate seed crystal has a high tap density and good Al uniformity. In the preparation process of cobalt carbonate precursor co-doped with aluminum and nickel, the low concentration ammonium bicarbonate solution provides sufficient carbonate ions for precipitation, and also helps to avoid precipitation. incomplete nickel caused by the fact that the solubility product of nickel carbonate is much higher than the solubility product of cobalt carbonate and aluminum hydroxide when nickel-cobalt-aluminum co-precipitation is carried out in a system of ammonium bicarbonate at high concentration, thus avoiding the loss of nickel in the supernatant. The resulting aluminum and nickel co-doped cobalt carbonate precursor exhibits a flake morphology to provide more growth sites for nickel co-precipitation, thereby reducing nickel loss. Such a structure has high porosity and good sintering activity to provide diffusion paths for nickel in the preparation process of tricobalt tetroxide, thereby improving the distribution uniformity of nickel and improving the performance of tricobalt tetroxide.

The reaction temperature of the cobalt carbonate precursor co-doped with aluminum and nickel in the present application is relatively low, the energy consumption is low, and the nucleation can be well controlled in the synthesis process, thereby ensuring the yield.

Other aspects can be understood after reading and understanding the drawings and detailed description.

The drawings are intended to provide a better understanding of the technical solutions herein, constitute a part of the description, illustrate the technical solutions herein in conjunction with embodiments of the present disclosure, and do not limit the technical solutions herein.

There represents morphological images of a cobalt carbonate seed crystal and a cobalt carbonate precursor co-doped with aluminum and nickel obtained in Example 1; where a is a scanning electron microscope image of the cobalt carbonate seed crystal, b and c are the scanning electron microscope images of the cobalt carbonate precursor co-doped with aluminum and nickel, and d is l CP cross-sectional image of cobalt carbonate precursor co-doped with aluminum and nickel;

There represents morphological images of a seed crystal of cobalt carbonate and of a precursor of cobalt carbonate co-doped with aluminum and nickel obtained in Example 2; where a is a scanning electron microscope image of the cobalt carbonate seed crystal, b and c are the scanning electron microscope images of the cobalt carbonate precursor co-doped with aluminum and nickel, and d is l CP cross-sectional image of cobalt carbonate precursor co-doped with aluminum and nickel;

There represents morphological images of a seed crystal of cobalt carbonate and of a precursor of cobalt carbonate co-doped with aluminum and nickel obtained in Example 3; where a is a scanning electron microscope image of the cobalt carbonate seed crystal, b and c are the scanning electron microscope images of the cobalt carbonate precursor co-doped with aluminum and nickel, and d is l CP cross-sectional image of cobalt carbonate precursor co-doped with aluminum and nickel;

There represents morphological images of a cobalt carbonate seed crystal and a cobalt carbonate precursor co-doped with aluminum and nickel obtained in Comparative Example 1; where a is a scanning electron microscope image of the cobalt carbonate seed crystal, b and c are the scanning electron microscope images of the cobalt carbonate precursor co-doped with aluminum and nickel, and d is l CP cross-sectional image of cobalt carbonate precursor co-doped with aluminum and nickel;

There represents morphological images of a cobalt carbonate seed crystal and a cobalt carbonate precursor co-doped with aluminum and nickel obtained in Comparative Example 2; where a is a scanning electron microscope image of the cobalt carbonate seed crystal, b and c are the scanning electron microscope images of the cobalt carbonate precursor co-doped with aluminum and nickel, and d is l CP cross-sectional image of cobalt carbonate precursor co-doped with aluminum and nickel; And

There represents morphological images of a cobalt carbonate seed crystal and a cobalt carbonate precursor co-doped with aluminum and nickel obtained in Comparative Example 6; where a is a scanning electron microscope image of the cobalt carbonate seed crystal, b and c are the scanning electron microscope images of the cobalt carbonate precursor co-doped with aluminum and nickel, and d is l CP cross-sectional image of cobalt carbonate precursor co-doped with aluminum and nickel.

DETAILED DESCRIPTION

To make the objects, technical solutions and advantages of the present application more apparent, an additional description is given below to illustrate the present application in conjunction with the examples and drawings.

Example 1

This example provides a process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel. The preparation process includes the following steps.

Solution preparation: Cobalt chloride solution, nickel sulfate solution, aluminum sulfate solution, high concentration ammonium bicarbonate solution, low concentration ammonium bicarbonate solution, and ammonium bicarbonate base solution were prepared, respectively, where the concentration of cobalt ions in the cobalt chloride solution was 130 g/L, the concentration of nickel ions in the nickel sulfate solution was 3 g/L, the concentration of aluminum ions in the aluminum sulfate solution was 12.8 g/L, the molar ratio of a complexing agent to aluminum ions was 1:10, the concentration of bicarbonate of ammonium in the high concentration ammonium bicarbonate solution was 237 g/L, the concentration of ammonium bicarbonate in the low concentration ammonium bicarbonate solution was 120 g/L and the concentration of ammonium bicarbonate of ammonium in the ammonium bicarbonate base solution was 40 g/L.

Preparation of cobalt carbonate seed crystal: The ammonium bicarbonate base solution was added to a 300 L reaction vessel, where the volume of the ammonium bicarbonate base solution was such that the palette of The lowest agitation was submerged and the pH of the base solution was 8.2. With stirring at a temperature of 41.8°C and a frequency of 20 Hz, the cobalt chloride solution, the aluminum sulfate solution and the high concentration ammonium bicarbonate solution were added in parallel flow , where the flow rate of the cobalt chloride solution was 7.5 L/h and the flow rate of the aluminum sulfate solution was 0.75 L/h, the flow rate of the ammonium bicarbonate solution at High concentration was adjusted via a PLC control system to keep the pH at the seed crystal synthesis stage between 7.6 and 8.0, and the parallel flow addition was carried out for 15 h. When the D ₅₀ of the material generated after the reaction reached 9 μm, the feeding was stopped to yield a seed crystal of cobalt carbonate.

Cobalt carbonate precursor co-doped with aluminum and nickel: The reaction temperature was increased to 45.5°C, and with stirring at a frequency of 20 Hz, the cobalt chloride solution, the cobalt chloride solution Nickel sulfate, aluminum sulfate solution, and low concentration ammonium bicarbonate solution were then added in parallel flow to the cobalt carbonate seed crystal in the reaction vessel, where the chloride solution flow of cobalt was 15 L/h, the flow rate of the aluminum sulfate solution was 1.5 L/h, the flow rate of the nickel sulfate solution was 1.5 L/h and the flow rate of the Low concentration ammonium bicarbonate solution was adjusted via the PLC control system to maintain the pH at the seed crystal growth stage between 7.0 and 7.2. When the volume of the reaction solution in the reaction vessel was 80% of the volume of the reaction vessel, the reaction solution was concentrated and the supernatant was removed, where the volume of the reaction solution was kept at 80% of the reaction vessel volume in the concentration process. When the D ₅₀ of the material generated after the reaction reached 18.3 µm, the feeding was stopped to yield a cobalt carbonate slurry.

The obtained cobalt carbonate suspension was subjected to centrifugal filtration, and the obtained filtered material was washed with ammonium bicarbonate solution at a temperature of 60°C for 30 min, where the concentration of ammonium bicarbonate in the ammonium bicarbonate solution was 25 g/L. The washed filtered material was subjected to centrifugal filtration again, and the obtained filtered material was dried at 110°C for 12 h until the moisture content of the filtered material was less than 1.1%, then sieved. through a 300 mesh vibrating screen to yield a cobalt carbonate precursor co-doped with aluminum and nickel.

Example 2

This example provides a process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel. The preparation process includes the following steps.

Solution preparation: Cobalt chloride solution, nickel sulfate solution, aluminum sulfate solution, high concentration ammonium bicarbonate solution, low concentration ammonium bicarbonate solution, and ammonium bicarbonate base solution were prepared, respectively, where the concentration of cobalt ions in the cobalt chloride solution was 100 g/L, the concentration of nickel ions in the nickel sulfate solution was 3 g/L, the concentration of aluminum ions in the aluminum sulfate solution was 12.8 g/L, the molar ratio of a complexing agent to aluminum ions was 1:10, the concentration of bicarbonate of ammonium in the high concentration ammonium bicarbonate solution was 237 g/L, the concentration of ammonium bicarbonate in the low concentration ammonium bicarbonate solution was 142 g/L and the concentration of ammonium bicarbonate of ammonium in the ammonium bicarbonate base solution was 40 g/L.

Preparation of cobalt carbonate seed crystal: The ammonium bicarbonate base solution was added to a 300 L reaction vessel, where the volume of the ammonium bicarbonate base solution was such that the palette of The lowest agitation was submerged and the pH of the base solution was 8.2. With stirring at a temperature of 41.5°C and a frequency of 20 Hz, the cobalt chloride solution, the aluminum sulfate solution and the high concentration ammonium bicarbonate solution were added in parallel flow , where the flow rate of the cobalt chloride solution was 10.3 L/h, the flow rate of the aluminum sulfate solution was 0.75 L/h, the flow rate of the ammonium bicarbonate solution at High concentration was adjusted via a PLC control system to keep the pH at the seed crystal synthesis stage between 7.7 and 8.1, and the parallel flow addition was carried out for 15 h. When the D ₅₀ of the material generated after the reaction reached 8.5 µm, the feeding was stopped to yield a seed crystal of cobalt carbonate.

Cobalt carbonate precursor co-doped with aluminum and nickel: The reaction temperature was increased to 45.3°C, and with stirring at a frequency of 20 Hz, the solution of cobalt chloride, the solution of Nickel sulfate, aluminum sulfate solution, and low concentration ammonium bicarbonate solution were then added in parallel flow to the cobalt carbonate seed crystal in the reaction vessel, where the chloride solution flow of cobalt was 20.6 L/h, the flow rate of the aluminum sulfate solution was 1.5 L/h, the flow rate of the nickel sulfate solution was 1.5 L/h, and the flow rate of the low concentration ammonium bicarbonate solution was adjusted via the PLC control system to maintain the pH at the seed crystal growth stage between 7.1 and 7.3. When the volume of the reaction solution in the reaction vessel was 83% of the volume of the reaction vessel, the reaction solution was concentrated and the supernatant was removed, where the volume of the reaction solution was kept at 83% of the reaction vessel volume in the concentration process. When the D ₅₀ of the material generated after the reaction reached 18.2 µm, the feeding was stopped to yield a cobalt carbonate slurry.

The obtained cobalt carbonate suspension was subjected to centrifugal filtration and the obtained filtered material was washed with ammonium bicarbonate solution at a temperature of 60°C for 30 min, where the concentration of ammonium bicarbonate in ammonium bicarbonate solution was 22 g/L. The washed filtered material was subjected to centrifugal filtration again, and the obtained filtered material was dried at 110°C for 12 h until the moisture content of the filtered material was less than 1.1%, then sieved. through a 300 mesh vibrating screen to yield a cobalt carbonate precursor co-doped with aluminum and nickel.

Example 3

This example provides a process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel. The preparation process includes the following steps.

Solution preparation: Cobalt chloride solution, nickel sulfate solution, aluminum sulfate solution, high concentration ammonium bicarbonate solution, low concentration ammonium bicarbonate solution, and ammonium bicarbonate base solution were prepared, respectively, where the concentration of cobalt ions in the cobalt chloride solution was 120 g/L, the concentration of nickel ions in the nickel sulfate solution was 3 g/L, the concentration of aluminum ions in the aluminum sulfate solution was 12.8 g/L, the molar ratio of a complexing agent to aluminum ions was 1:10, the complexing agent was disodium ethylenediaminetetraacetic acid, the concentration of ammonium bicarbonate in the high concentration ammonium bicarbonate solution was 237 g/L, the concentration of ammonium bicarbonate in the low concentration ammonium bicarbonate solution was was 142 g/L, and the concentration of ammonium bicarbonate in the ammonium bicarbonate base solution was 40 g/L.

Preparation of cobalt carbonate seed crystal: The ammonium bicarbonate base solution was added to a 300 L reaction vessel, where the volume of the ammonium bicarbonate base solution was such that the palette of The lowest agitation was submerged and the pH of the base solution was 8.1. Under stirring at a temperature of 40.7°C and a frequency of 20 Hz, the cobalt chloride solution, the aluminum sulfate solution and the high concentration ammonium bicarbonate solution were added in parallel flow , where the flow rate of the cobalt chloride solution was 8.3 L/h, the flow rate of the aluminum sulfate solution was 0.75 L/h, the flow rate of the ammonium bicarbonate solution was High concentration was adjusted via a PLC control system to keep the pH at the seed crystal synthesis stage between 7.7 and 8.1, and the parallel flow addition was carried out for 15 h. When the D ₅₀ of the material generated after the reaction reached 7.9 µm, the feeding was stopped to yield a seed crystal of cobalt carbonate.

Cobalt carbonate precursor co-doped with aluminum and nickel: The reaction temperature was increased to 45.6°C, and with stirring at a frequency of 20 Hz, the cobalt chloride solution, the cobalt chloride solution Nickel sulfate, aluminum sulfate solution, and low concentration ammonium bicarbonate solution were then added in parallel flow to the cobalt carbonate seed crystal in the reaction vessel, where the chloride solution flow of cobalt was 16.5 L/h, the flow rate of the aluminum sulfate solution was 1.5 L/h, the flow rate of the nickel sulfate solution was 1.5 L/h, and the flow rate of the low concentration ammonium bicarbonate solution was adjusted via the PLC control system to maintain the pH at the seed crystal growth stage between 7.1 and 7.3. When the volume of the reaction solution in the reaction vessel was 81% of the volume of the reaction vessel, the reaction solution was concentrated and the supernatant was removed, where the volume of the reaction solution was kept at 81% of the reaction vessel volume in the concentration process. When the D ₅₀ of the material generated after the reaction reached 18.4 µm, the feeding was stopped to yield a cobalt carbonate slurry.

The obtained cobalt carbonate suspension was subjected to centrifugal filtration and the obtained filtered material was washed with ammonium bicarbonate solution at a temperature of 60°C for 30 min, where the concentration of ammonium bicarbonate in ammonium bicarbonate solution was 23 g/L. The washed filtered material was subjected to centrifugal filtration again, and the obtained filtered material was dried at 110°C for 12 h until the moisture content of the filtered material was less than 2.2%, then sieved. through a 300 mesh vibrating screen to yield a cobalt carbonate precursor co-doped with aluminum and nickel.

Example 4

This example provides a process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel. The preparation process includes the following steps.

Solution preparation: Cobalt chloride solution, nickel sulfate solution, aluminum sulfate solution, high concentration ammonium bicarbonate solution, low concentration ammonium bicarbonate solution, and ammonium bicarbonate base solution were prepared, respectively, where the concentration of cobalt ions in the cobalt chloride solution was 120 g/L, the concentration of nickel ions in the nickel sulfate solution was 10 g/L, the concentration of aluminum ions in the aluminum sulfate solution was 15 g/L, the molar ratio of a complexing agent to aluminum ions was 1:10, the complexing agent was ammonium citrate, the concentration of ammonium bicarbonate in the high concentration ammonium bicarbonate solution was 220 g/L, the concentration of ammonium bicarbonate in the low concentration ammonium bicarbonate solution was 120 g/L, and the concentration of ammonium bicarbonate in the ammonium bicarbonate base solution was 80 g/L.

Preparation of cobalt carbonate seed crystal: The ammonium bicarbonate base solution was added to a 300 L reaction vessel, where the volume of the ammonium bicarbonate base solution was such that the palette of The lowest agitation was submerged and the pH of the base solution was 8.5. With stirring at a temperature of 38.1°C and a frequency of 20 Hz, the cobalt chloride solution, the aluminum sulfate solution and the high concentration ammonium bicarbonate solution were added in parallel flow , where the flow rate of the cobalt chloride solution was 3.5 L/h, the flow rate of the aluminum sulfate solution was 0.27 L/h, the flow rate of the ammonium bicarbonate solution was High concentration was adjusted via a PLC control system to keep the pH at the seed crystal synthesis stage between 7.7 and 8.1, and parallel flow addition was carried out for 15 h. When the D ₅₀ of the material generated after the reaction reached 7.2 µm, the feeding was stopped to yield a seed crystal of cobalt carbonate.

Cobalt carbonate precursor co-doped with aluminum and nickel: The reaction temperature was increased to 54.8°C, and with stirring at a frequency of 20 Hz, the cobalt chloride solution, the cobalt chloride solution Nickel sulfate, aluminum sulfate solution, and low concentration ammonium bicarbonate solution were then added in parallel flow to the cobalt carbonate seed crystal in the reaction vessel, where the chloride solution flow of cobalt was 16.5 L/h, the flow rate of the aluminum sulfate solution was 1.2 L/h, the flow rate of the nickel sulfate solution was 0.45 L/h, and the flow rate of the low concentration ammonium bicarbonate solution was adjusted via the PLC control system to maintain the pH at the seed crystal growth stage between 7.1 and 7.3. When the volume of the reaction solution in the reaction vessel was 81% of the volume of the reaction vessel, the reaction solution was concentrated and the supernatant was removed, where the volume of the reaction solution was maintained to 81% of the reaction vessel volume in the concentration process. When the D ₅₀ of the material generated after the reaction reached 19.6 µm, the feeding was stopped to yield a cobalt carbonate slurry.

The obtained cobalt carbonate suspension was subjected to centrifugal filtration and the obtained filtered material was washed with ammonium bicarbonate solution at a temperature of 50°C for 60 min, where the concentration of ammonium bicarbonate in the ammonium bicarbonate solution was 10 g/L. The washed filtered material was subjected to centrifugal filtration again, and the obtained filtered material was dried at 90°C for 12 h until the moisture content of the filtered material was less than 2.2%, then sieved. through a 300 mesh vibrating screen to yield a cobalt carbonate precursor co-doped with aluminum and nickel.

Example 5

This example provides a process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel. The preparation process includes the following steps.

Solution preparation: Cobalt chloride solution, nickel sulfate solution, aluminum sulfate solution, high concentration ammonium bicarbonate solution, low concentration ammonium bicarbonate solution, and ammonium bicarbonate base solution were prepared, respectively, where the concentration of cobalt ions in the cobalt chloride solution was 120 g/L, the concentration of nickel ions in the nickel sulfate solution was 1 g/L, the concentration of aluminum ions in the aluminum sulfate solution was 5 g/L, the molar ratio of a complexing agent to aluminum ions was 0.5:10, the complexing agent was tartaric acid, the concentration of ammonium bicarbonate in the high concentration ammonium bicarbonate solution was 230 g/L, the concentration of ammonium bicarbonate in the low concentration ammonium bicarbonate solution was of 179 g/L, and the concentration of ammonium bicarbonate in the ammonium bicarbonate base solution was 120 g/L.

Preparation of cobalt carbonate seed crystal: The ammonium bicarbonate base solution was added to a 300 L reaction vessel, where the volume of the ammonium bicarbonate base solution was such that the palette of The lowest agitation was submerged and the pH of the base solution was 8.1. With stirring at a temperature of 44.7°C and a frequency of 20 Hz, the cobalt chloride solution, the aluminum sulfate solution and the high concentration ammonium bicarbonate solution were added in parallel flow , where the flow rate of cobalt chloride solution was 15 L/h, the flow rate of aluminum sulfate solution was 3.47 L/h, the flow rate of high concentration ammonium bicarbonate solution was adjusted via a PLC control system to keep the pH at the seed crystal synthesis stage between 7.7 and 8.1, and the parallel flow addition was carried out for 15 h. When the D ₅₀ of the material generated after the reaction reached 7.9 µm, the feeding was stopped to yield a seed crystal of cobalt carbonate.

Cobalt carbonate precursor co-doped with aluminum and nickel: The reaction temperature was increased to 50.6°C, and with stirring at a frequency of 20 Hz, the cobalt chloride solution, the cobalt chloride solution Nickel sulfate, aluminum sulfate solution, and low concentration ammonium bicarbonate solution were then added in parallel flow to the cobalt carbonate seed crystal in the reaction vessel, where the chloride solution flow of cobalt was 16.5 L/h, the flow rate of the aluminum sulfate solution was 3.84 L/h, the flow rate of the nickel sulfate solution was 4.5 L/h, and the flow rate of the low concentration ammonium bicarbonate solution was adjusted via the PLC control system to maintain the pH at the seed crystal growth stage between 7.1 and 7.3. When the volume of the reaction solution in the reaction vessel was 81% of the volume of the reaction vessel, the reaction solution was concentrated and the supernatant was removed, where the volume of the reaction solution was kept at 81% of the reaction vessel volume in the concentration process. When the D₅₀of Material generated after the reaction reached 15.4 µm, the feed was stopped to give a suspension of cobalt carbonate.

The obtained cobalt carbonate suspension was subjected to centrifugal filtration and the obtained filtered material was washed with ammonium bicarbonate solution at a temperature of 60°C for 10 min, where the concentration of ammonium bicarbonate in the ammonium bicarbonate solution was 50 g/L. The washed filtered material was subjected to centrifugal filtration again, and the obtained filtered material was dried at 100°C for 12 h until the moisture content of the filtered material was less than 2.2%, then sieved. through a 300 mesh vibrating screen to yield a cobalt carbonate precursor co-doped with aluminum and nickel.

Comparative Example 1

The only difference between this comparative example and Example 1 was that the low concentration ammonium bicarbonate solution was not contained in this comparative example.

Comparative Example 2

The only difference between this comparative example and Example 1 was that the high concentration ammonium bicarbonate solution was not contained in this comparative example.

Comparative Example 3

The only difference between this comparative example and Example 1 was that the aluminum sulfate solution did not contain any complexing agent in this comparative example.

Comparative Example 4

This example provides a process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel. The preparation process includes the following steps.

Solution preparation: Mixed solution, high concentration ammonium bicarbonate solution, low concentration ammonium bicarbonate solution and base ammonium bicarbonate solution were prepared, respectively, where the concentrations of cobalt ions, nickel ions and aluminum ions in the mixed solution were 130 g/L, 0.3 g/L and 1.28 g/L, respectively, the molar ratio of a complexing agent to the aluminum ions was 1:10, the concentration of ammonium bicarbonate in the high concentration ammonium bicarbonate solution was 237 g/L, the concentration of ammonium bicarbonate in the low concentration ammonium bicarbonate solution was concentration was 120 g/L, and the concentration of ammonium bicarbonate in the ammonium bicarbonate base solution was 40 g/L.

Preparation of cobalt carbonate seed crystal: The ammonium bicarbonate base solution was added to a 300 L reaction vessel, where the volume of the ammonium bicarbonate base solution was such that the palette of The lowest agitation was submerged and the pH of the base solution was 8.2. Under stirring at a temperature of 41.8°C and a frequency of 20 Hz, the mixed solution and the high concentration ammonium bicarbonate solution were added in parallel flow, where the flow rate of the mixed solution was 7 .5 L/h, the flow rate of high concentration ammonium bicarbonate solution was adjusted through a PLC control system to keep the pH at the seed crystal synthesis stage between 7.6 and 8 ,0, and the addition in parallel flow was carried out for 15 h. When the D ₅₀ of the material generated after the reaction reached 9 μm, the feeding was stopped to yield a seed crystal of cobalt carbonate.

Cobalt carbonate precursor co-doped with aluminum and nickel: The reaction temperature was increased to 45.5°C, and with stirring at a frequency of 20 Hz, the mixed solution and the bicarbonate solution of ammonium at low concentration were then added in parallel flow to the seed crystal of cobalt carbonate in the reaction vessel, where the flow rate of the mixed solution was 15 L/h, and the flow rate of the ammonium bicarbonate solution at Low concentration was adjusted through the PLC control system to maintain the pH at the seed crystal growth stage between 7.0 and 7.2. When the volume of the reaction solution in the reaction vessel was 80% of the volume of the reaction vessel, the reaction solution was concentrated and the supernatant was removed, where the volume of the reaction solution was kept at 80% of the reaction vessel volume in the concentration process. When the D ₅₀ of the material generated after the reaction reached 18.3 µm, the feeding was stopped to yield a cobalt carbonate slurry.

The obtained cobalt carbonate suspension was subjected to centrifugal filtration and the obtained filtered material was washed with ammonium bicarbonate solution at a temperature of 60°C for 30 min, where the concentration of ammonium bicarbonate in the ammonium bicarbonate solution was 25 g/L. The washed filtered material was subjected to centrifugal filtration again, and the obtained filtered material was dried at 110°C for 12 h until the moisture content of the filtered material was less than 1.1%, then sieved. through a 300 mesh vibrating screen to yield a cobalt carbonate precursor co-doped with aluminum and nickel.

Comparative Example 5

This example provides a process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel. The preparation process includes the following steps.

Solution preparation: Cobalt chloride solution, nickel sulfate solution, aluminum sulfate solution, high concentration sodium carbonate solution, low concentration sodium carbonate solution, and sodium carbonate solution sodium carbonate base were prepared, respectively, where the concentration of cobalt ions in the cobalt chloride solution was 130 g/L, the concentration of nickel ions in the nickel sulfate solution was 3 g/ L, the concentration of aluminum ions in the aluminum sulfate solution was 12.8 g/L, the molar ratio of a complexing agent to aluminum ions was 1:10, the concentration of sodium carbonate in the high concentration sodium carbonate solution was 237 g/L, the concentration of sodium carbonate in the low concentration sodium carbonate solution was 120 g/L, and the concentration of sodium carbonate in the base solution was 120 g/L of sodium carbonate was 40 g/L.

Preparation of cobalt carbonate seed crystal: The sodium carbonate base solution was added to a 300 L reaction vessel, where the volume of the sodium carbonate base solution was such that the stirring paddle lower was submerged and the pH of the base solution was 8.2. With stirring at a temperature of 41.8°C and a frequency of 20 Hz, the cobalt chloride solution, the aluminum sulfate solution and the sodium carbonate solution at high concentration were added in parallel flow, where the flow rate of cobalt chloride solution was 7.5 L/h, the flow rate of aluminum sulfate solution was 0.75 L/h, the flow rate of high concentration sodium carbonate solution was adjusted via a PLC control system to keep the pH at the seed crystal synthesis stage between 7.6 and 8.0, and parallel flow addition was carried out for 15 h. When the D ₅₀ of the material generated after the reaction reached 9 μm, the feeding was stopped to yield a seed crystal of cobalt carbonate.

Cobalt carbonate precursor co-doped with aluminum and nickel: The reaction temperature was increased to 45.5°C, and with stirring at a frequency of 20 Hz, the cobalt chloride solution, the cobalt chloride solution Nickel sulfate, aluminum sulfate solution, and low concentration sodium carbonate solution were then added in parallel flow to the cobalt carbonate seed crystal in the reaction vessel, where the flow of nickel chloride solution cobalt solution was 15 L/h, the flow rate of the aluminum sulfate solution was 1.5 L/h, the flow rate of the nickel sulfate solution was 1.5 L/h, and the flow rate of the solution Low concentration sodium carbonate was adjusted via the PLC control system to maintain the pH at the seed crystal growth stage between 7.0 and 7.2. When the volume of the reaction solution in the reaction vessel was 80% of the volume of the reaction vessel, the reaction solution was concentrated and the supernatant was removed, where the volume of the reaction solution was kept at 80% of the reaction vessel volume in the concentration process. When the D ₅₀ of the material generated after the reaction reached 18.3 µm, the feeding was stopped to yield a cobalt carbonate slurry.

The obtained cobalt carbonate suspension was subjected to centrifugal filtration and the obtained filtered material was washed with a pure water solution at a temperature of 60°C for 30 min, where the concentration of pure water in the solution of pure water was 25 g/L. The washed filtered material was subjected to centrifugal filtration again, and the obtained filtered material was dried at 110°C for 12 h until the moisture content of the filtered material was less than 1.1%, then sieved. through a 300 mesh vibrating screen to yield a cobalt carbonate precursor co-doped with aluminum and nickel.

Comparative Example 6

This example provides a process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel. The preparation process includes the following steps.

Solution preparation: Mixed saline solution, sodium carbonate solution, aqueous ammonia solution and sodium carbonate base solution were prepared, respectively, where in the mixed solution, the concentration of cobalt ions in cobalt chloride was 130 g/L, the concentration of aluminum ions was 1.28 g/L, and the concentration of nickel in nickel sulfate solution was 0.3 g/L; the concentration of sodium carbonate in the sodium carbonate solution was 120 g/L, the mass fraction of aqueous ammonia in the aqueous ammonia solution was 10%, and the concentration of sodium carbonate in the solution of sodium carbonate base was 40 g/L.

Preparation of cobalt carbonate seed crystal: The sodium carbonate base solution was added to a 300 L reaction vessel, where the volume of the sodium carbonate base solution was such that the stirring paddle lower was submerged and the pH of the base solution was 8.5. With stirring at a temperature of 45.3°C and a frequency of 20 Hz, the mixed solution and the sodium carbonate solution were added in parallel flow, where the flow rate of the mixed solution was 7.5 L/ h, the flow rate of sodium carbonate solution was adjusted via a PLC control system to keep the pH at the seed crystal synthesis stage between 7.3 and 7.4, and adding in Parallel flow was carried out for 15 h. When the D ₅₀ of the material generated after the reaction reached 7.3 µm, the feeding was stopped to yield a seed crystal of cobalt carbonate.

Cobalt carbonate precursor co-doped with aluminum and nickel: The reaction temperature was increased to 45.7°C, and with stirring at a frequency of 20 Hz, the mixed solution and the sodium carbonate solution were then added in parallel flow to the cobalt carbonate seed crystal in the reaction vessel, where the flow rate of the mixed solution was 15 L/h, and the flow rate of the sodium carbonate solution was adjusted by the Intermediate PLC control system to keep the pH at seed crystal growth stage between 7.2 and 7.4. Aqueous ammonia was added in parallel flow, where the concentration of aqueous ammonia in the reaction system was regulated between 0.5 and 1 g/L. When the volume of the reaction solution in the reaction vessel was 80% of the volume of the reaction vessel, the reaction solution was concentrated and the supernatant was removed, where the volume of the reaction solution was kept at 80% of the reaction vessel volume in the concentration process. When the D ₅₀ of the material generated after the reaction reached 18.3 µm, the feeding was stopped to yield a cobalt carbonate slurry.

The obtained cobalt carbonate suspension was subjected to centrifugal filtration and the obtained filtered material was washed with pure water at a temperature of 60°C for 30 min. The washed filtered material was subjected to centrifugal filtration again and the obtained filtered material was dried at 110°C for 12 h until the moisture content of the filtered material was 2.6%, then sieved at through a 300 mesh vibrating screen to yield a cobalt carbonate precursor co-doped with aluminum and nickel.

Experimental Example 1

The morphologies of the cobalt carbonate seed crystals and cobalt carbonate precursors co-doped with aluminum and nickel obtained were tested, and the results are presented in the has . There is the scanning electron microscope image of the cobalt carbonate precursor co-doped with aluminum and nickel obtained in Example 1, the is the scanning electron microscope image of the cobalt carbonate precursor co-doped with aluminum and nickel obtained in Example 2; there is the scanning electron microscope image of the cobalt carbonate precursor co-doped with aluminum and nickel obtained in Example 1, the is the scanning electron microscope image of the cobalt carbonate precursor co-doped with aluminum and nickel obtained in Comparative Example 1, the is the scanning electron microscope image of the cobalt carbonate precursor co-doped with aluminum and nickel obtained in Comparative Example 2, and the is the scanning electron microscope image of the cobalt carbonate precursor co-doped with aluminum and nickel obtained in Comparative Example 6. As can be seen in the has , the cobalt carbonate precursors co-doped with aluminum and nickel obtained in Examples 1 to 3 have sharply accumulated flakes on the surface, no micropowder or nucleation occurs, and the precursors have good sphericity particles and good particle size uniformity; as shown in the CP cross-section images, the interior of the precursors is smooth, no segregation occurs, the distribution of elements is uniform, the inner layer of the particle is compact, and the outer layer of the particle has high porosity to some extent, which is related to the fact that cobalt carbonate precursors co-doped with aluminum and nickel have a bulk structure in the inner layer and a flake structure in the outer layer. As can be seen on the , the outer layer of the cobalt carbonate precursor co-doped with aluminum and nickel obtained in Comparative Example 1 is seriously segregated; As shown in the CP cross-section image, the inner and outer layers of the particle are seriously segregated, with radial segregation, the distribution of elements is not uniform, and the inner layer of the particle is compact, which is related to the bulk structure of the primary particle. As can be seen on the , the cobalt carbonate precursor co-doped with aluminum and nickel obtained in Comparative Example 2 has particles and flakes mixed in a cutting structure on the surface; as shown in the CP cross-section image, the interior of the particle is seriously segregated, the distribution of elements is not uniform, the inner layer of the particle is compact, and the outer layer of the particle has high porosity to some extent, which is related to the fact that cobalt carbonate has a bulk structure in the inner layer and a flake structure in the outer layer. As can be seen on the , the surface of the cobalt carbonate precursor co-doped with aluminum and nickel obtained in Comparative Example 6 is seriously segregated, and nucleation occurs to a certain extent; As shown in the CP cross-section image, the interior of the particle is seriously segregated, the distribution of elements is not uniform, and the inner layer of the particle is compact, which is related to the bulk structure of the primary particle.

Experimental Example 2

The cobalt carbonate precursors co-doped with aluminum and nickel obtained in Examples 1 to 5 and Comparative Examples 1 to 6 were each heated to 300°C at a rate of 3°C/min in an atmosphere of air and calcined for 3 h, then were heated to 700°C at a rate of 3°C/min, calcined for 3 h, and cooled by oven cooling to give tricobalt tetroxide. The resulting tricobalt tetroxide was mixed with lithium carbonate and calcined to prepare lithium cobaltate. With lithium cobaltate as the positive electrode and lithium metal foil as the negative electrode, a button cell battery was prepared. With a charge/discharge voltage in the range of 3.0 V to 4.65 V, the initial specific discharge capacity was tested at a rate of 0.1 C, and the capacity retention rate was tested by cycling the battery for 50 cycles at a rate of 0.5 C. The test results are shown in [Table 1].

Specific initial discharge capacity (mAg/g) Capacity retention rate /% Example 1 190.3 88.6 Example 2 191.5 89.1 Example 3 190.5 89.7 Example 4 190.8 88.9 Example 5 191.3 88.2 Comparative Example 1 184.5 83.2 Comparative Example 2 185.3 81.6 Comparative Example 3 183.3 84.1 Comparative Example 4 184.1 82.8 Comparative Example 5 187.4 76.5 Comparative Example 6 188.5 78.2

As shown in Table 1, the batteries prepared from the cobalt carbonate precursors co-doped with aluminum and nickel of Examples 1 to 6 have a higher capacity and better cycling performance, compared to the batteries prepared from the cobalt carbonate precursors co-doped with aluminum and nickel of the Comparative Examples.

Finally, it should be noted that the above examples are used to illustrate the technical solutions of this application and should not be construed as a limitation of the scope of this application. Although the present application has been described in detail with reference to preferred examples thereof, those skilled in the art will understand that equivalent modifications or substitutions of the technical solutions of the present application can be made without deviating from the spirit and scope of the technical solutions of this application.

Claims (10)

Process for preparing a cobalt carbonate precursor co-doped with aluminum and nickel, comprising the following steps:
preparation of the solution: the preparation of a cobalt salt solution, a nickel salt solution, an aluminum salt solution, a high concentration ammonium bicarbonate solution, a low concentration ammonium bicarbonate solution and a base ammonium bicarbonate solution, respectively; where the concentration of cobalt ions in the cobalt salt solution is 100 to 130 g/L, the concentration of nickel ions in the nickel salt solution is 1 to 10 g/L, the concentration of nickel ions aluminum in aluminum salt solution is 5 to 15 g/L, the concentration of ammonium bicarbonate in high concentration ammonium bicarbonate solution is 220 to 240 g/L, the concentration of bicarbonate d ammonium in the low concentration ammonium bicarbonate solution is 120 to 180 g/L, and the concentration of ammonium bicarbonate in the basic ammonium bicarbonate solution is 40 to 120 g/L;
preparation of cobalt carbonate seed crystal: adding the ammonium bicarbonate base solution to a reaction vessel, adding the cobalt salt solution, the aluminum salt solution and the high concentration ammonium bicarbonate solution in parallel flow with heating and stirring, and the reaction to generate a cobalt carbonate seed crystal; And
preparation of cobalt carbonate precursor co-doped with aluminum and nickel: then adding the cobalt salt solution, the nickel salt solution, the aluminum salt solution and the solution of ammonium bicarbonate at low concentration to the seed crystal of cobalt carbonate in the reaction vessel in parallel flow with heating and stirring; filtering the material obtained from the reaction, and washing, drying and grinding the filtered material obtained to obtain a cobalt carbonate precursor co-doped with aluminum and nickel. Preparation process according to claim 1, wherein the aluminum salt solution comprises a complexing agent, and the molar ratio of the complexing agent to aluminum is (0.5 to 1):10; preferably, the complexing agent is at least one of disodium ethylenediaminetetraacetic acid, ammonium citrate, citric acid, tartaric acid or sulfosalicylic acid. A preparation method according to claim 1, wherein in the preparation of cobalt carbonate seed crystal, heating is carried out at a temperature of 38 to 45°C. A preparation method according to claim 1, wherein in the preparation of cobalt carbonate seed crystal, the pH of the base solution is 8 to 9, the pH of the reaction solution is regulated to be between 7.5 and 8.1 in the feeding process, and the flow rate of the cobalt salt solution per hour is 1% to 5% of the volume of the reaction tank. Preparation method according to claim 1, wherein in the preparation of cobalt carbonate precursor co-doped with aluminum and nickel, the heating is carried out at a temperature of 45 to 55°C. A preparation method according to claim 1, wherein in the preparation of cobalt carbonate precursor co-doped with aluminum and nickel, the pH of the reaction solution is regulated to be between 7.0 and 7.5 in the feeding process, and the flow rate of cobalt salt solution per hour is 1% to 5% of the volume of the reaction vessel. Preparation process according to claim 1, in which at least one of the following criteria (a) to (g) is satisfied:
(a) the cobalt salt is at least one of cobalt chloride, cobalt sulfate and/or cobalt nitrate;
(b) the nickel salt is at least one of nickel sulfate or nickel chloride;
(c) the aluminum salt is at least one of aluminum chloride or aluminum sulfate;
(d) the D ₅₀ of the cobalt carbonate seed crystal is 7 to 13 µm;
(e) the D ₅₀ of the material obtained from the reaction is 15 to 20 μm;
(f) the solvent used in washing is pure water or ammonium bicarbonate solution;
(g) washing is carried out at a temperature of 25 to 80°C. Cobalt carbonate precursor co-doped with aluminum and nickel, prepared by the preparation process according to any one of claims 1 to 7. A cathode material precursor, wherein the raw material for preparing the cathode material precursor comprises the cobalt carbonate precursor co-doped with aluminum and nickel according to claim 8. A cathode material, wherein the raw material for preparing the cathode material comprises the cathode material precursor according to claim 9 or the cobalt carbonate precursor co-doped with aluminum and nickel according to claim 8.