CN116262633A

CN116262633A - A kind of cobalt carbonate, tricobalt tetroxide, positive electrode material and preparation method

Info

Publication number: CN116262633A
Application number: CN202211005843.1A
Authority: CN
Inventors: 夏勇; 訚硕; 翁毅; 周明涛; 黄明; 胡俊康; 冯朝勇; 卿毕尧
Original assignee: Hunan Zhongwei New Energy Technology Co ltd
Current assignee: Hunan Zhongwei New Energy Technology Co ltd
Priority date: 2022-08-22
Filing date: 2022-08-22
Publication date: 2023-06-16
Anticipated expiration: 2042-08-22
Also published as: CN116262633B

Abstract

The application provides a cobalt carbonate, cobaltosic oxide, a positive electrode material and a preparation method thereof, relates to the technical field of new energy, and has a pore volume of 0.01-0.10 cm ³ The prepared cobaltosic oxide has high compactness, uniform element distribution and uniform pore distribution, and the pore volume is 0.0010-0.0090 cm ³ And/g, through the distribution of a large number of micropores and mesopores, the activity of the material is improved, and the discharge capacity and the cycle performance of the battery are improved.

Description

Cobalt carbonate, cobaltosic oxide, positive electrode material and preparation method

Technical Field

The application relates to the technical field of new energy, in particular to cobalt carbonate, cobaltosic oxide, a positive electrode material and a preparation method.

Background

With the updating of electronic equipment in the 3C field, particularly the performance of various aspects of smart phones is greatly improved, so that higher requirements are put forward on the aspects of battery capacity, circulation, safety performance and the like in the equipment. In the prior art, the energy density of the lithium ion battery is improved and the cycle performance of the lithium ion battery is improved by increasing the charge cut-off voltage and increasing the compaction density of the positive electrode material, but the improvement on the structure and physical and chemical indexes of the precursor of the positive electrode material, such as cobalt carbonate and a cobaltosic oxide product prepared from the precursor is less.

Disclosure of Invention

The present application aims to provide cobalt carbonate, cobaltosic oxide, a positive electrode material and a preparation method thereof, and aims to improve battery performance by improving structural performance of a precursor of the positive electrode material, such as cobalt carbonate and cobaltosic oxide prepared by the precursor.

To achieve the above object, the present application provides a tricobalt tetraoxide having a porous interior, a uniform pore distribution, and a pore distribution fitting R ² The value > 0.9.

Preferably, the aperture of the cobaltosic oxide is 1.0-4.5 nm;

preferably, the specific surface area of the cobaltosic oxide is 1 to 5m ² /g；

Preferably, the tap density of the cobaltosic oxide is 2.6-3.0 g/cm ³ ；

Preferably, the median particle size of the tricobalt tetraoxide is 14-19 μm;

preferably, the pore volume is 0.0010 to 0.0090cm ³ /g。

Preferably, the cobaltosic oxide comprises doping elements, wherein the doping elements are selected from one or more of Al, mg, ni, mn, la, zr, ti, W;

preferably, the doping mass contents of the doping elements are respectively: 0.40 to 1.20 percent of Al, 0.08 to 0.50 percent of Mg, 0.10 to 3.00 percent of Ni, 0.10 to 3.00 percent of Mn, 0.05 to 0.30 percent of La, 0.10 to 0.30 percent of Zr, 0.05 to 0.30 percent of Ti and 0.10 to 0.50 percent of W;

preferably, the pore volume is 0.0013-0.0020 cm ³ /g。

The application also provides the cobalt carbonate for preparing the cobaltosic oxide, which has the advantages of consistent internal pore diameter and uniform pore distribution, and the pore volume of the cobalt carbonate is 0.01-0.10 cm ³ /g。

Preferably, the aperture of the cobalt carbonate is 1.0-4.0 nm;

preferably, the specific surface area of the cobalt carbonate is 40-130 m ² /g；

Preferably, the tap density of the cobalt carbonate is 1.4-2.0 g/cm ³ ；

Preferably, the median particle size of the cobalt carbonate is 16 to 22. Mu.m.

The application also provides a preparation method of the cobalt carbonate, which comprises the following steps:

adding a cobalt salt solution and a precipitant solution into a reaction kettle containing a base solution for reaction, wherein the flow rate of the cobalt salt solution is increased along with the increase of the granularity of a material, the stirring rotation speed of the reaction kettle is reduced along with the increase of the granularity of the material, and continuously reacting to the target granularity to obtain cobalt carbonate slurry;

and (3) centrifugally washing the cobalt carbonate slurry to obtain cobalt carbonate.

Preferably, the cobalt salt solution is selected from a cobalt sulphate solution and/or a cobalt chloride solution; the precipitant solution is selected from ammonium bicarbonate solution and/or sodium carbonate solution, and the base solution is selected from ammonium bicarbonate solution and/or sodium carbonate solution;

preferably, the cobalt concentration in the cobalt salt solution is 90-130 g/L, and the concentration of the precipitant solution is 190-230 g/L; the concentration of the base solution is 5-50 g/L;

Preferably, the cobalt salt solution comprises doping elements selected from one or more of Al, mg, ni, mn, la, zr, ti, W, wherein the doping elements exist in the form of sulfate;

preferably, the doping elements in the cobalt carbonate have the following doping mass contents: 0.26 to 0.70 percent of Al, 0.05 to 0.33 percent of Mg, 0.06 to 2.00 percent of Ni, 0.06 to 2.00 percent of Mn, 0.03 to 0.20 percent of La, 0.06 to 0.20 percent of Zr, 0.03 to 0.20 percent of Ti and 0.06 to 0.33 percent of W.

Preferably, the flow rate of the cobalt salt solution is 2-6% per hour of the available volume of the reaction kettle, and the stirring rotating speed of the reaction kettle is 300-100 r/min;

preferably, the target particle size of the cobalt carbonate is 16 to 22 μm.

The application also provides a preparation method of the cobaltosic oxide, which comprises the following steps:

providing the cobalt carbonate or the cobalt carbonate prepared by the preparation method of the cobalt carbonate;

and sintering the cobalt carbonate to obtain the cobaltosic oxide.

Preferably, the sintering temperature is 700-850 ℃.

Preferably, the cobalt carbonate is preheated before being sintered, the preheating temperature is 200-500 ℃, and the preheating time is 20-60 min;

preferably, when the rotary kiln is used for sintering, the rotation frequency of the furnace tube of the rotary kiln is 0.5-1.5 r/min, and the thickness of the material layer is less than or equal to 16cm.

The application also provides a positive electrode material, which is lithium cobaltate obtained by calcining the cobaltosic oxide and a lithium source;

preferably, the molar ratio of the lithium source to the tricobalt tetraoxide is 1 to 1.05;

preferably, the calcination temperature is 900-1200 ℃ and the calcination time is 20-30 h.

Compared with the prior art, the beneficial effects of this application include:

the pore volume of the cobalt carbonate provided by the application is 0.01-0.10 cm ³ The cobalt carbonate is rapidly and uniformly contracted in the sintering process, and the prepared cobaltosic oxide has uniform distribution of elements and pores, and the pore volume is 0.0010-0.0090 cm ³ On the one hand, can provide a large number of micropores and mesopores,and certain compactness of the particles is maintained, and the activity of the material is improved and the discharge capacity and the cycle performance of the battery are improved through the distribution of a large number of micropores and mesopores.

Drawings

FIG. 1 is a scanning electron microscope topography of the cobalt carbonate particles of example 1;

FIG. 2 is a scanning electron microscope topography of a cut surface of the cobalt carbonate particles of example 1;

FIG. 3 is a scanning electron microscope topography of the tricobalt tetraoxide of example 1;

FIG. 4 is a scanning electron microscope topography of a cross-section of tricobalt tetraoxide of example 1;

FIG. 5 is a graph showing the results of analysis of the Al component of the cobaltosic oxide micro-region of example 1;

FIG. 6 is a scanning electron microscope topography of the cobalt carbonate particles of example 2;

FIG. 7 is a scanning electron microscope topography of the tricobalt tetraoxide of example 2;

FIG. 8 is a scanning electron microscope topography of a cross-section of tricobalt tetraoxide of example 2;

FIG. 9 is a graph showing the results of analysis of the Ni content of the micro region of tricobalt tetraoxide of example 2;

FIG. 10 is a graph showing the results of analysis of Mn content in the micro domains of tricobalt tetraoxide of example 2;

FIG. 11 is a scanning electron microscope topography of the cobalt carbonate particles of example 3;

FIG. 12 is a scanning electron microscope topography of a cut surface of the cobalt carbonate particles of example 3;

FIG. 13 is a scanning electron microscope topography of the tricobalt tetraoxide of example 3;

FIG. 14 is a scanning electron microscope topography of a cross section of tricobalt tetraoxide of example 3;

FIG. 15 is a graph of the correlation coefficient of the area of the region and the area of the pores of the tricobalt tetraoxide of example 3;

FIG. 16 is a graph showing the results of analysis of the Al content of the micro-domains of tricobalt tetraoxide of example 3;

FIG. 17 is a graph showing the results of analysis of the Mg composition in the micro-domains of tricobalt tetraoxide of example 3;

FIG. 18 is a scanning electron microscope topography of the cobalt carbonate particles of example 4;

FIG. 19 is a scanning electron microscope topography of the tricobalt tetraoxide of example 4;

FIG. 20 is a scanning electron microscope topography of a tricobalt tetraoxide section of example 4;

FIG. 21 is a graph showing the results of analysis of the Al content of the micro-domains of tricobalt tetraoxide of example 4;

FIG. 22 is a scanning electron microscope topography of the cobalt carbonate particles of comparative example 1;

FIG. 23 is a scanning electron microscope topography of the tricobalt tetraoxide of comparative example 1;

FIG. 24 is a scanning electron microscope topography of a tricobalt tetraoxide section of comparative example 1.

Detailed Description

The application provides a cobaltosic oxide, wherein the inside of the cobaltosic oxide is porous, the pore distribution of the cobaltosic oxide is uniform, and the pore distribution of the cobaltosic oxide is fitted with R ² The value is more than 0.9, and the pore volume of the cobaltosic oxide is 0.0013-0.0020 cm ³ And/g. The cobaltosic oxide is a raw material for preparing the lithium cobalt oxide positive electrode material, lithium cobalt oxide is obtained by calcining the cobaltosic oxide and a lithium source, and the performance of the cobaltosic oxide determines the performance of the lithium cobalt oxide positive electrode material and has inheritance.

The porosity of the cobaltosic oxide is 10-45%, the porosity of the cobaltosic oxide= (the area of the inner cross-sectional pore area of the cobaltosic oxide/the area of the cross-sectional area of the cobaltosic oxide) is 100%, the inner porosity of the cobaltosic oxide is a range of values, not limited to a specific value, and the porosities of different parts may be different, for example, the porosities may be 10-20%, 20-30%, or 30-45%. In further examples, the porosity may be, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, or 45%.

The porosity distribution fitting R of the cobaltosic oxide ² Value > 0.9, porosity distribution fitting R ² The specific verification steps for representing the uniformity of pore distribution are as follows:

step one: the single cobaltosic oxide particles are regarded as spheres, the calculation is carried out according to the cross section circle of the spheres, and the circles are equally divided into n (n is more than or equal to 3) concentric circles;

step two: calculating the difference between the area of each concentric circle and the area of the adjacent concentric circle, and the pore area of the corresponding area;

step three: calculating the change x of the cross-sectional areas of different areas and the change y of the pore areas of corresponding areas;

step four: establishing a linear relation between x and y, and calculating a correlation coefficient R ² ；

When R is ² And if the pore size is more than or equal to 0.9, the pore size is considered to be uniformly distributed. Wherein when R is ² When the pore size is between 0.9 and 0.95, the pore size distribution is considered to be relatively uniform, and when R ² When the pore size is more than or equal to 0.95, the pore distribution height is considered to be uniform;

when R is ² At < 0.9, the pore distribution is considered to be non-uniform.

The pore volume of the cobaltosic oxide is 0.0010-0.0090 cm ³ For example, the pore volume of the tricobalt tetraoxide may be 0.0010 to 0.0015cm ³ /g，0.0013～0.0017cm ³ /g，0.0015～0.0020cm ³ /g，0.0016～0.0020cm ³ /g，0.0020～0.0030cm ³ /g，0.0030～0.0040cm ³ /g，0.0040～0.0050cm ³ /g，0.0050～0.0070cm ³ Per g, or 0.0070-0.0090 cm ³ And/g. In a further example, the pore volume of the tricobalt tetraoxide may be 0.0013cm ³ /g、0.0014cm ³ /g、0.0015cm ³ /g、0.0016cm ³ /g、0.0017cm ³ /g、0.0018cm ³ /g、0.0019cm ³ /g、0.0020cm ³ /g、0.0025cm ³ /g、0.0030cm ³ /g、0.0034cm ³ /g、0.0039cm ³ /g、0.0043cm ³ /g、0.0047cm ³ /g、0.0052cm ³ /g、0.0065cm ³ /g、0.0067cm ³ /g、0.0071cm ³ /g、0.0076cm ³ /g、0.0081cm ³ Per gram, or 0.0085cm ³ /g。

The cobaltosic oxide has the advantages that the pore distribution is highly uniform, a large number of micropores and mesopores which are uniformly distributed are provided for the penetration passage of the lithium salt into the particles in the reaction process of the lithium salt in the process of synthesizing the lithium cobalt oxide anode material, the reaction activity is improved, the development of lithium cobalt oxide unit cells is improved, the stability of a crystal structure is improved, and the cycle performance is improved. The proper pore volume can improve the electrochemical performance of the material and simultaneously avoid the great reduction of tap density and compaction density, so that the material has better volume energy density.

Preferably, the pore size of the cobaltosic oxide is 1.0-4.5 nm. For example, the pore size of the tricobalt tetraoxide may be 1.0 to 3.0nm, 2.0 to 4.5nm, 1.0 to 2.5nm, or 2.0 to 4.0nm. In further examples, the pore size of the tricobalt tetraoxide may be 1.0nm, 2.0nm, 3.0nm, 4.0nm, or 4.5nm.

The smaller pore diameter can ensure that a large number of channels exist in the particles, and simultaneously ensure smaller pore volume, higher tap density and improved specific capacity of the material.

Preferably, the specific surface area of the cobaltosic oxide is 1 to 5m ² And/g. For example, the specific surface area of the tricobalt tetraoxide may be 1.0 to 2.0m ² /g、1.5～3.5m ² /g、2.0～4.0m ² /g, or 3.0-5.0 m ² And/g. In a further example, the specific surface area of the tricobalt tetraoxide may be 1.0m ² /g、2.0m ² /g、3.0m ² /g、4.0m ² /g, or 5.0m ² /g。

The material activity can be improved by adopting the proper specific surface area.

Preferably, the tap density of the cobaltosic oxide is 2.6-3.0 g/cm ³ . For example, the tap density of the tricobalt tetraoxide may be 2.6 to 2.7g/cm ³ 、2.7～3.0g/cm ³ 、2.7～2.8g/cm ³ Or 2.8 to 3.0g/cm ³ . In a further example, the tap density of the tricobalt tetraoxide may be 2.6g/cm ³ 、2.65g/cm ³ 、2.7g/cm ³ 、2.75g/cm ³ 、2.8g/cm ³ 、2.85g/cm ³ 、2.9g/cm ³ 、2.95g/cm ³ Or 3.0g/cm ³ 。

The cobaltosic oxide has higher tap density, so that the compaction density of the lithium cobaltate serving as the positive electrode material can be improved, and the specific capacity of the material can be improved.

Preferably, the median particle size of the tricobalt tetraoxide is 14 to 19 μm. For example, the median particle size of the tricobalt tetraoxide may be 14 to 16 μm, 15 to 18 μm, or 17 to 19 μm. In further examples, the median particle size of the tricobalt tetraoxide may be 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, or 19 μm.

Preferably, the cobaltosic oxide comprises doping elements selected from one or more of Al, mg, ni, mn, la, zr, ti, W.

Preferably, the doping mass contents of the doping elements are respectively: 0.40 to 1.20 percent of Al, 0.08 to 0.50 percent of Mg, 0.10 to 3.00 percent of Ni, 0.10 to 3.00 percent of Mn, 0.05 to 0.30 percent of La, 0.10 to 0.30 percent of Zr, 0.05 to 0.30 percent of Ti and 0.10 to 0.50 percent of W.

The application also provides the cobalt carbonate which is a raw material for preparing the cobaltosic oxide, wherein the cobalt carbonate is used for preparing the cobaltosic oxide, and the internal pore diameters of the cobalt carbonate are consistent, namely the difference value between the pore diameter sizes detected in different growth processes of cobalt carbonate particles and the pore diameter size at the end of the cobalt carbonate is less than 20%; the pore distribution of the cobalt carbonate is uniform, and the pore volume of the cobalt carbonate is 0.01-0.10 cm ³ And/g. For example, the pore volume of the cobalt carbonate may be 0.01 to 0.04cm ³ /g、0.02～0.06cm ³ Per gram, or 0.05 to 0.09cm ³ And/g. In a further example, the pore volume of the cobalt carbonate may be 0.01cm ³ /g、0.02cm ³ /g、0.03cm ³ /g、0.04cm ³ /g、0.05cm ³ /g、0.06cm ³ /g、0.07cm ³ /g、0.08cm ³ /g, or 0.09cm ³ /g。

Preferably, the pore size of the cobalt carbonate is 1.0 to 4.0nm. For example, the pore size of the cobalt carbonate may be 1.0 to 3.0nm, 2.0 to 4.0nm, or 3.0 to 4.0nm. In further examples, the pore size of the cobalt carbonate may be 1.0nm, 2.0nm, 3.0nm, or 4.0nm.

Preferably, carbonic acidThe specific surface area of cobalt is 40-130 m ² And/g. For example, the specific surface area of the cobalt carbonate may be 40 to 60m ² /g、50～80m ² /g、70～100m ² Per gram, or 110-130 m ² And/g. In a further example, the specific surface area of the cobalt carbonate may be 40m ² /g、45m ² /g、50m ² /g、55m ² /g、60m ² /g、65m ² /g、70m ² /g、75m ² /g、80m ² /g、85m ² /g、90m ² /g、95m ² /g、100m ² /g、110m ² /g、115m ² /g、120m ² /g, or 130m ² /g。

Preferably, the tap density of the cobalt carbonate is 1.4-2.0 g/cm ³ . For example, the tap density of the cobalt carbonate may be 1.4 to 1.7g/cm ³ 、1.6～1.8g/cm ³ Or 1.5 to 2.0g/cm ³ . In a further example, the tap density of the cobalt carbonate may be 1.4g/cm ³ 、1.5g/cm ³ 、1.6g/cm ³ 、1.7g/cm ³ 、1.8g/cm ³ 、1.9g/cm ³ Or 2.0g/cm ³ 。

Preferably, the median particle size of the cobalt carbonate is 16 to 22. Mu.m. For example, the median particle size of the cobalt carbonate may be 16 to 18 μm, 17 to 20 μm, or 18 to 22 μm. In further examples, the median particle size of the cobalt carbonate may be 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm, 20 μm, 20.5 μm, 21 μm, 21.5 μm, or 22 μm

Specifically, the cobalt salt solution is selected from a cobalt sulfate solution and/or a cobalt chloride solution; the precipitant solution is selected from ammonium bicarbonate solution and/or sodium carbonate solution; the base solution is selected from ammonium bicarbonate solution and/or sodium carbonate solution;

the cobalt salt solution has a cobalt concentration of 90 to 130g/L, and may be, for example, (90, 91, 93, 95, 96, 98, 100, 102, 105, 106, 108, 110, 112, 115, 116, 118, 120, 122, 123, 126, 128 or 130) g/L.

Preferably, the concentration of the precipitant solution is 190-230 g/L; the concentration of the base solution is 5-50 g/L;

preferably, the cobalt salt solution comprises doping elements selected from one or more of Al, mg, ni, mn, la, zr, ti, W;

preferably, the doping elements in the cobalt carbonate have the following doping mass contents: 0.26 to 0.70 percent of Al, 0.05 to 0.33 percent of Mg, 0.06 to 2.00 percent of Ni, 0.06 to 2.00 percent of Mn, 0.03 to 0.20 percent of La, 0.06 to 0.20 percent of Zr, 0.03 to 0.20 percent of Ti and 0.06 to 0.33 percent of W;

in a preferred embodiment, the flow rate of the cobalt salt solution is in the range of 2 to 6% per hour of the available volume of the reaction vessel, for example, the flow rate of the cobalt salt solution may be 2%, 3%, 4%, 5%, or 6% per hour of the available volume of the reaction vessel. The stirring speed of the reaction kettle is 300-100 r/min, and can be (300, 250, 200, 150 or 100) r/min, for example.

Preferably, the target particle size of the cobalt carbonate is 16 to 22 μm.

and sintering the cobalt carbonate to obtain the cobaltosic oxide.

Preferably, the sintering temperature is 700-850 ℃.

For example, the sintering temperature may be (700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 810, 820, 830, 840, or 850) deg.c.

Preferably, the method further comprises preheating the cobalt carbonate before sintering, wherein the preheating temperature is 200-500 ℃, and the preheating time is 20-60 min. The preheating section is lower in temperature and longer in time, and the shrinkage of the cobaltosic oxide is uniform.

Preferably, when the rotary kiln is used for sintering, the rotation frequency of the furnace tube of the rotary kiln is 0.5-1.5 r/min, and the thickness of the material layer is less than or equal to 16cm. The thinner the layer, the more uniform the heating, and the more uniform the pores of the resulting tricobalt tetraoxide.

The application also provides a positive electrode material, and lithium cobaltate is obtained by calcining the cobaltate and a lithium source.

Preferably, the molar ratio of the lithium source to the tricobalt tetraoxide is 1 to 1.05.

Preferably, the calcination temperature is 900 to 1200 ℃, and may be, for example, (900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, or 1200) DEG C. The calcination time is 20 to 30 hours, and may be (20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30) hours, for example.

Embodiments of the present application will be described in detail below with reference to specific examples, but it will be understood by those skilled in the art that the following examples are only for illustration of the present application and should not be construed as limiting the scope of the present application. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Example 1

1. Mixing a cobalt sulfate solution and an aluminum sulfate solution to prepare an aluminum-doped cobalt salt solution, wherein the cobalt concentration in the solution is 90g/L, and the molar ratio of cobalt to aluminum in the solution is as follows: co: al=1:0.0139, and preparing ammonium bicarbonate solution with mass concentration of 190g/L as precipitant solution; preparing ammonium bicarbonate solution with the mass concentration of 10g/L as base solution.

2. Adding the prepared cobalt salt solution and the precipitant solution into a reaction kettle containing base solution at the same time for reaction, wherein the flow rate of the cobalt salt solution is 3 percent/h of the available volume of the reaction kettle, the stirring rotation speed is maintained to be 300r/min for the first 6h, and then the stirring rotation speed is reduced to 250r/min until the granularity grows to 9 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow of the cobalt salt solution to 4 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 250r/min for the first 6h, and reducing the stirring rotation speed to 200r/min until the granularity grows to 13 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow of the cobalt salt solution to 5 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed for 200r/min in the first 6h, reducing the stirring rotation speed to 150r/min, and growing the granularity to 17 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow rate of the cobalt salt solution to 6 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 150r/min for the first 6h, reducing the stirring rotation speed to 100r/min, and growing the granularity to 20.5 mu m; the aluminum doped cobalt carbonate of example 1 was prepared.

The results of the scanning electron microscope morphology of the cobalt carbonate particles of example 1 are shown in FIG. 1, the morphology of the section scanning electron microscope is shown in FIG. 2, and the specific surface area of the cobalt carbonate particles of example 1 is 110m ² Per g, average pore diameter of 1.77nm, pore volume of 0.06cm ³ /g。

3. And (3) carrying out centrifugal washing on the cobalt carbonate, and then sintering, wherein the temperature of a preheating section is 500 ℃, the residence time of the preheating section is 20min, the high-temperature sintering temperature is 800 ℃, the sintering time is 3h, the rotation frequency of a rotary kiln furnace tube is 1.0r/min, and the thickness of a material layer is 16cm, so that the aluminum-doped cobaltosic oxide of the embodiment 1 is prepared.

The morphology of the scanning electron microscope of the cobaltosic oxide of example 1 is shown in FIG. 3, the morphology of the section scanning electron microscope of the cobaltosic oxide of example 1 is shown in FIG. 4, the median diameter D50=17.02 μm of the cobaltosic oxide of example 1 is shown in FIG. 4, and the specific surface area is 2.5m ² Per gram, average pore diameter of 1.99nm, pore volume of 0.0015cm ³ Per gram, tap density of 2.85g/cm ³ Degree of fit R of porosity distribution ² A value of 0.912, a porosity distribution fitness R ² The calculation method of the values is shown with reference to example 3. The Al composition of the fine particle region was analyzed by using an electron probe apparatus in the tricobalt tetraoxide of example 1, and the Al element distribution was uniform as shown in fig. 5.

The lithium cobaltate positive electrode material of example 1 was prepared by uniformly mixing the cobaltate obtained in example 1 with lithium carbonate in a molar ratio of Li/Me of 1.05:1 and calcining at 1060℃for 24 hours.

Example 2

1. Mixing a cobalt sulfate solution with an aluminum sulfate, nickel sulfate and a manganese sulfate solution to prepare a cobalt salt solution doped with aluminum, nickel and manganese, wherein the cobalt concentration in the solution is 110g/L, and the molar ratio of the aluminum, the nickel, the manganese and the cobalt in the solution is as follows: co: al: ni: mn=1:0.0139:0.0035:0.0055, and preparing an ammonium bicarbonate solution with a mass concentration of 190g/L as a precipitant solution; preparing ammonium bicarbonate solution with the mass concentration of 10g/L as base solution.

2. Adding the prepared cobalt salt solution and the precipitant solution into a reaction kettle containing base solution at the same time for reaction, wherein the flow rate of the cobalt salt solution is 3 percent/h of the available volume of the reaction kettle, the stirring rotation speed is maintained to be 300/min for the first 6h, and then the stirring rotation speed is reduced to 250r/min until the granularity grows to 7 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow of the cobalt salt solution to 4 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 250r/min for the first 6h, and reducing the stirring rotation speed to 200r/min until the granularity grows to 10 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow of the cobalt salt solution to 5 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed for 200r/min for the first 6h, and reducing the stirring rotation speed to 150r/min until the granularity grows to 14 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow rate of the cobalt salt solution to 6 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 150r/min for the first 6h, and reducing the stirring rotation speed to 100r/min until the granularity grows to 16.0 mu m; the cobalt carbonate doped with aluminum, nickel, manganese of example 2 was prepared.

The morphology of the cobalt carbonate particles of example 2 is shown in FIG. 6, and the cobalt carbonate of example 2 has been detected to have a specific surface area of 45m ² Per gram, average pore diameter of 1.57nm, pore volume of 0.04cm ³ /g。

3. And (3) carrying out sintering after centrifugal washing on the cobalt carbonate, wherein the temperature of a preheating section is 350 ℃, the retention time of the preheating section is 30min, the high-temperature sintering temperature is 850 ℃, the sintering time is 3h, the rotation frequency of a rotary kiln furnace tube is 0.5r/min, and the thickness of a material layer is less than 6cm. The aluminum, nickel, manganese doped tricobalt tetraoxide of example 2 was prepared.

The morphology of the scanning electron microscope of the cobaltosic oxide of example 2 is shown in FIG. 7, the morphology of the section scanning electron microscope of the cobaltosic oxide of example 2 is shown in FIG. 8, the median diameter D50=14.52 μm, and the specific surface area of the cobaltosic oxide of example 2 is 1.5m ² Per gram, average pore diameter of 1.82nm, pore volume of 0.0019cm ³ Per gram, tap density of 2.60g/cm ³ Degree of fit R of porosity distribution ² The value was 0.902. The tricobalt tetraoxide of example 2 was analyzed for Ni and Mn components in the micro-regions of the particles using an electron probe instrument, and the results were shown in FIGS. 9 and 10, respectively, in which the Ni element and Mn element were uniformly distributed.

The lithium cobaltate positive electrode material of example 2 was prepared by uniformly mixing the cobaltate obtained in example 2 with lithium carbonate in a molar ratio of Li/Me of 1.05:1 and calcining at 1030℃for 24 hours.

Example 3

1. Mixing a cobalt chloride solution, aluminum sulfate and a magnesium sulfate solution to prepare an aluminum-magnesium-doped cobalt salt solution, wherein the cobalt concentration in the solution is 120g/L, and the molar ratio of the aluminum to the magnesium to the cobalt in the solution is as follows: co: al: mg=1:0.0083:0.0056, and preparing a sodium carbonate solution with a mass concentration of 190g/L as a precipitant solution; preparing sodium carbonate solution with the mass concentration of 10g/L as base solution.

2. Adding the prepared cobalt salt solution and the precipitant solution into a reaction kettle containing base solution at the same time for reaction, wherein the flow rate of the cobalt salt solution is 3 percent/h of the available volume of the reaction kettle, the stirring rotation speed is maintained for 300r/min for the first 6h, and then the stirring rotation speed is reduced to 250r/min until the granularity grows to 9.5 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow of the cobalt salt solution to 5 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed for 200r/min for the first 6h, and reducing the stirring rotation speed to 150r/min until the granularity grows to 17 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow rate of the cobalt salt solution to 6 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 150r/min for the first 6h, and reducing the stirring rotation speed to 100r/min until the granularity grows to 22.0 mu m; the aluminum and magnesium doped cobalt carbonate of example 3 was prepared.

The specific surface area, pore diameter and pore volume of the cobalt carbonate of example 3 were measured at particle diameters of 5 μm, 10 μm, 15 μm and 22 μm, respectively, and the results are shown in Table 1, which demonstrate that the pore diameter and pore distribution of the particles in the cobalt carbonate were uniform.

Table 1 cobalt carbonate growth process ratio table, pore size, pore volume for example 3

Particle size μm	Specific surface area m ² /g	Average pore diameter nm	Pore volume cm ³ /g
				5	115	2.02	0.09
10	103	2.05	0.09
				15	110	2.10	0.08
22	125	2.26	0.08

The scanning electron microscope morphology of the cobalt carbonate particles obtained in example 3 is shown in FIG. 11, and the tangential scanning electron microscope morphology is shown in FIG. 12.

3. And (3) carrying out centrifugal washing on the cobalt carbonate, and then sintering, wherein the temperature of a preheating section is 300 ℃, the retention time of the preheating section is 45min, the high-temperature sintering temperature is 700 ℃, the sintering time is 3h, the rotation frequency of a rotary kiln furnace tube is 1.0r/min, and the thickness of a material layer is 16cm, so that the aluminum and magnesium doped cobaltosic oxide is prepared.

The morphology of the scanning electron microscope of the cobaltosic oxide of example 3 is shown in FIG. 13, the median particle diameter D50=18.81 μm of the cobaltosic oxide of example 3, and the specific surface area is 5.3m ² Per gram, average pore diameter of 2.51nm, pore volume of 0.0013cm ³ Per gram, tap density of 2.95g/cm ³ Degree of fit R of porosity distribution ² The value was 0.993.

Degree of fit R of porosity distribution ² The calculation mode of the value is as follows: the tricobalt tetraoxide of example 3 was taken for cutting and photographing the electron microscope, the cut portion was divided into four regions (1) (2) (3) (4), as shown in fig. 14, the analysis image processing (gap gray scale 1-100, total area 1-256) was performed on the cut electron microscope using PS and IPP software, and the relative porosities of the respective regions were calculated as shown in table 2. R is obtained by calculating the correlation coefficient of the area of the region and the area of the pore ² =0.993 > 0.98, as shown in fig. 15, indicating that the sample porosity distribution is uniform.

TABLE 2 tricobalt tetraoxide porosities of example 3

Region(s)	Area of aperture	Area of aperture	Calculation of porosity%
				①	42111	11651	28
②	126331	41542	33
				③	210552	80215	38
④	294773	119855	41
				①+②	168442	53193	32
①+②+③	378994	133408	35
				①+②+③+④	673767	249621	37

The tricobalt tetraoxide of example 3 was analyzed for Al and Mg components in the micro-region of the particles using an electron probe instrument, and the results were shown in fig. 16 and 17, respectively, in which Al and Mg elements were uniformly distributed.

The lithium cobaltate positive electrode material of example 3 was prepared by uniformly mixing the cobaltate obtained in example 3 with lithium carbonate in a molar ratio of Li/Me of 1.05:1 and calcining at 1020℃for 24 hours.

Example 4

1. Mixing a cobalt sulfate solution with a zirconium sulfate solution and a lanthanum sulfate solution to prepare a cobalt salt solution doped with Zr and La, wherein the cobalt concentration in the solution is 130g/L, and the ratio of Zr and La to cobalt in the solution is as follows: co: la=1:0.0111:0.0056, and preparing ammonium bicarbonate solution with mass concentration of 190g/L as precipitant solution; preparing ammonium bicarbonate solution with the mass concentration of 10g/L as base solution.

Half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, improving the flow rate of cobalt liquid to 4 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 250r/min for the first 6h, and reducing the stirring rotation speed to 200r/min until the granularity grows to 13 mu m.

Half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, improving the flow rate of cobalt liquid to 5 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed for 200r/min for the first 6h, and reducing the stirring rotation speed to 150r/min until the granularity grows to 17 mu m.

Half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow rate of cobalt liquid to 6 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 150r/min for the first 6h, and reducing the stirring rotation speed to 100r/min until the granularity grows to 21.0 mu m; zr and La doped cobalt carbonate of example 4 was prepared.

The morphology of the cobalt carbonate particles of example 4 is shown in FIG. 18, and the cobalt carbonate of example 4 has been detected to have a specific surface area of 121m ² Per gram, average pore diameter of 3.9nm, pore volume of 0.09cm ³ /g。

3. And (3) carrying out centrifugal washing on the cobalt carbonate, and then sintering, wherein the temperature of a preheating section is 200 ℃, the residence time of the preheating section is 60min, the high-temperature sintering temperature is 780 ℃, the sintering time is 3h, the rotation frequency of a rotary kiln furnace tube is 1.5r/min, and the thickness of a material layer is 10cm, so that the Zr and La doped cobaltosic oxide is prepared.

The morphology of the scanning electron microscope of the cobaltosic oxide of example 4 is shown in FIG. 19, the morphology of the section scanning electron microscope of the cobaltosic oxide of example 4 is shown in FIG. 20, the median diameter d50=17.50 μm of the cobaltosic oxide of example 4, and the specific surface area is 3.1m ² Per g, average pore diameter of 4.23nm, pore volume of 0.0020cm ³ Per gram, tap density of 2.78g/cm ³ Degree of fit R of porosity distribution ² The value was 0.964.

The Al composition of the fine particle region was analyzed by using an electron probe apparatus in the tricobalt tetraoxide of example 4, and the Al element distribution was uniform as shown in fig. 21.

The lithium cobaltate positive electrode material of example 4 was prepared by uniformly mixing the cobaltate obtained in example 4 with lithium carbonate in a molar ratio of Li/Me of 1.05:1 and calcining at 1010℃for 24 hours.

Example 5

1. Preparing a cobalt sulfate solution, wherein the cobalt concentration in the solution is 90g/L, and preparing an ammonium bicarbonate solution with the mass concentration of 190g/L as a precipitant solution; preparing ammonium bicarbonate solution with the mass concentration of 10g/L as base solution.

2. Adding the prepared cobalt salt solution and the precipitant solution into a reaction kettle containing base solution at the same time for reaction, wherein the flow rate of the cobalt salt solution is 3 percent/h of the available volume of the reaction kettle, the stirring rotation speed is maintained for 300r/min for the first 6h, and then the stirring rotation speed is reduced to 250r/min until the granularity grows to 9 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow rate of the cobalt salt solution to 6 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 150r/min for the first 6h, and reducing the stirring rotation speed to 100r/min until the granularity grows to 20.5 mu m; cobalt carbonate of example 5 was prepared without doping elements.

The cobalt carbonate of example 5 was tested and had a specific surface area of 101m ² Per g, average pore diameter of 1.97nm, pore volume of 0.06cm ³ /g。

4. And (3) carrying out centrifugal washing on the cobalt carbonate, and then sintering, wherein the temperature of a preheating section is 500 ℃, the residence time of the preheating section is 20min, the high-temperature sintering temperature is 790 ℃, and the sintering time is 3h, so as to prepare the cobaltosic oxide without doping elements in the embodiment 5.

The median particle diameter d50=17.50 μm of the tricobalt tetraoxide of example 5, the specific surface area was 2.8m ² Per gram, average pore diameter of 1.87nm, pore volume of 0.0015cm ³ Per gram, tap density of 2.75g/cm ³ Degree of fit R of porosity distribution ² The value is 0.923, and the porosity distribution fitting degree R ² The calculation method of the values is shown with reference to example 3.

The lithium cobaltate positive electrode material of example 5 was prepared by uniformly mixing the cobaltate obtained in example 5 with lithium carbonate in a molar ratio of Li/Me of 1.05:1 and calcining at 1020℃for 24 hours.

Example 6

1. Mixing a cobalt sulfate solution and an aluminum sulfate solution to prepare an aluminum-doped cobalt salt solution, wherein the cobalt concentration in the solution is 100g/L, and the molar ratio of the cobalt to the aluminum in the solution is as follows: co: al=1:0.0139, and preparing an ammonium bicarbonate solution with a mass concentration of 200g/L as a precipitant solution; preparing ammonium bicarbonate solution with the mass concentration of 10g/L as base solution.

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow rate of the cobalt salt solution to 6 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 150r/min for the first 6h, and reducing the stirring rotation speed to 100r/min until the granularity grows to 20.5 mu m; the performance parameters of the aluminum doped cobalt carbonate of example 6 were prepared and are shown in Table 3.

3. The cobalt carbonate is centrifugally washed and then sintered, the temperature of a preheating section is 300 ℃, the retention time of the preheating section is 45min, the high-temperature sintering temperature is 800 ℃, and the sintering time is 3h, so that the aluminum-doped cobaltosic oxide of the embodiment 6 is prepared, and the performance parameters are shown in the table 4.

The lithium cobaltate cathode material of example 1 was prepared by uniformly mixing the cobaltate obtained in example 6 with lithium carbonate in a molar ratio of Li/Me of 1.05:1 and calcining at 1060℃for 24 hours.

Example 7

1. Mixing a cobalt sulfate solution and an aluminum sulfate solution to prepare an aluminum-doped cobalt salt solution, wherein the cobalt concentration in the solution is 100g/L, and the molar ratio of cobalt to aluminum in the solution is as follows: co: al=1:0.0139, and preparing an ammonium bicarbonate solution with a mass concentration of 200g/L as a precipitant solution; preparing ammonium bicarbonate solution with the mass concentration of 10g/L as base solution.

2. Adding the prepared cobalt salt solution and the precipitant solution into a reaction kettle containing base solution at the same time for reaction, wherein the flow rate of the cobalt salt solution is 3.5 percent/h of the available volume of the reaction kettle, the stirring rotation speed is maintained for 300r/min for the first 6h, and then the stirring rotation speed is reduced to 250r/min until the granularity grows to 9 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow rate of the cobalt salt solution to 4.5 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 250r/min for the first 6h, and reducing the stirring rotation speed to 200r/min until the granularity grows to 13 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow of the cobalt salt solution to 5.5 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed for 200r/min in the first 6h, and reducing the stirring rotation speed to 150r/min until the granularity grows to 17 mu m;

half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow rate of the cobalt salt solution to 6.5 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 150r/min for the first 6h, and reducing the stirring rotation speed to 100r/min until the granularity grows to 20.6 mu m; the performance parameters of the aluminum doped cobalt carbonate of example 7 were prepared and are shown in Table 3.

3. The cobalt carbonate is centrifugally washed and then sintered, the temperature of a preheating section is 250 ℃, the retention time of the preheating section is 60min, the high-temperature sintering temperature is 810 ℃, and the sintering time is 3h, so that the aluminum-doped cobaltosic oxide of the embodiment 7 is prepared, and the performance parameters are shown in the table 4.

The lithium cobaltate positive electrode material of example 7 was prepared by uniformly mixing the cobaltate obtained in example 7 with lithium carbonate in a molar ratio of Li/Me of 1.05:1 and calcining at 1060℃for 24 hours.

Example 8

Half of the materials in the reaction kettle are separated out and are continuously reacted for 2 hours according to the process. Changing the process, increasing the flow rate of the cobalt salt solution to 6.5 percent/h of the available volume of the reaction kettle, maintaining the stirring rotation speed at 150r/min for the first 6h, and reducing the stirring rotation speed to 110r/min until the granularity grows to 20.5 mu m; the performance parameters of the aluminum doped cobalt carbonate of example 8 were prepared and are shown in Table 3.

3. The cobalt carbonate is centrifugally washed and then sintered, the temperature of a preheating section is 260 ℃, the retention time of the preheating section is 60min, the high-temperature sintering temperature is 710 ℃, and the sintering time is 3h, so that the aluminum-doped cobaltosic oxide of the embodiment 8 is prepared, and the performance parameters are shown in the table 4.

The lithium cobaltate positive electrode material of example 8 was prepared by uniformly mixing the cobaltate obtained in example 8 with lithium carbonate in a molar ratio of Li/Me of 1.05:1 and calcining at 1050℃for 24 hours.

Comparative example 1

1. Mixing a cobalt sulfate solution and an aluminum sulfate solution to prepare an aluminum-doped cobalt salt solution, wherein the concentration of cobalt in the solution is 120g/L, and the ratio of aluminum to cobalt in the solution is as follows: co: al=1:0.0139, and preparing ammonium bicarbonate solution with mass concentration of 190g/L as precipitant solution; preparing ammonium bicarbonate solution with the mass concentration of 10g/L as base solution.

2. And (3) adding the prepared cobalt salt solution and the precipitant solution into a reaction kettle containing base solution at the same time for reaction, wherein the flow rate of the cobalt salt solution is 4 percent/h of the available volume of the reaction kettle, the stirring speed is 150r/min, and the granularity grows to 18.0 mu m, so as to prepare the aluminum-doped cobalt carbonate of the comparative example 1.

The morphology of the cobalt carbonate particles of comparative example 1 is shown in FIG. 22, and the cobalt carbonate of comparative example 1 has been detected to have a specific surface area of 4m ² Per gram, average pore diameter of 9.70nm and pore volume of 0.005cm ³ /g。

3. And (3) carrying out centrifugal washing on the cobalt carbonate, and then sintering at the temperature of 750 ℃ for 1.5 hours to prepare the aluminum-doped cobaltosic oxide of the comparative example 1.

The morphology of the scanning electron microscope of the cobaltosic oxide of comparative example 1 is shown in FIG. 23, the morphology of the section scanning electron microscope of the cobaltosic oxide of comparative example 1 is shown in FIG. 24, the median particle diameter D50=17.10 μm of the cobaltosic oxide of comparative example 1 is 2.0m ² Per g, average pore diameter of 6.12nm, pore volume of 0.0021cm ³ Per gram, tap density of 2.50g/cm ³ Degree of fit R of porosity distribution ² The value is 0.812.

Uniformly mixing the cobaltosic oxide obtained in the comparative example 1 with lithium carbonate according to the molar ratio of Li/Me of 1.05:1, and calcining at 1020 ℃ for 24 hours to prepare the lithium cobaltate anode material in the comparative example 1.

The indexes of the cobalt carbonate in each example and the comparative example are shown in table 3, and according to table 3, it is clear that in the process of the preparation method of cobalt carbonate in comparative example 1, the flow rate of cobalt salt solution is not increased along with the increase of the granularity of the material, the stirring rotation speed of the reaction kettle is not reduced along with the increase of the granularity of the material, and the whole process adopts the same flow rate and the same stirring rotation speed, so that the obtained cobalt carbonate has large average pore diameter, small specific surface area and small pore volume.

TABLE 3 index of cobalt carbonate for each example and comparative example

The index of the cobaltosic oxide of each example and comparative example is shown in Table 4, wherein examples 1 to 5 are respectively cobaltosic oxides with different doping elements and doping contents, the sintering process of examples 6 to 8 is different from that of example 1, the average pore diameter of the cobaltosic oxide of comparative example 1 is larger, and the porosity distribution fitting degree R ² The value is less than 0.9.

Table 4 index of tricobalt tetraoxide of each of examples and comparative examples

Test examples

The positive electrode materials of the examples and the comparative examples are respectively dissolved in NMP solvent according to the mass ratio of 85:10:5 with conductive carbon black and polyvinylidene fluoride to prepare positive electrode slurry with 80% of weight solid content. And then coating, drying and punching to prepare the anode wafer. Then preparing a lithium battery according to the sequence of the positive electrode shell, the positive electrode plate, the diaphragm, the negative electrode plate, the stainless steel sheet, the spring piece and the negative electrode shell, wherein the electrolyte is 1mol/LLiPF added with 10% (volume fraction) fluoroethylene carbonate (FEC) ₆ EC DMC (1:1 by volume), the separator is a polypropylene microporous membrane, and batteries of examples 1 to 8 and comparative example 1, respectively, were prepared, and the battery properties of each example and comparative example are shown in table 5.

Table 5 battery performance of each of examples and comparative examples

As can be seen from table 5, the batteries of examples 1 to 8 can improve discharge capacity and cycle performance relative to the comparative example, wherein the cathode material of example 5 is inferior to other examples in cycle performance due to the absence of the doping element. Wherein, example 6 compared with example 1, the cobaltosic oxide pore distribution is more uniform, and the capacity and the cycle performance of the battery are improved. Example 7 has a large pore volume and a small tap density of tricobalt tetraoxide compared with example 1, and the battery capacity is reduced; but the pores are more uniform and thus the cycle performance is better.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A tricobalt tetroxide, characterized in that the interior of the tricobalt tetroxide is porous, the pore distribution of the tricobalt tetroxide is uniform, and the porosity distribution fitting ^R2 value of the tricobalt tetroxide is >0.9.

2. The tricobalt tetroxide according to claim 1, characterized in that, the pore diameter of the tricobalt tetroxide is 1.0-4.5nm;

Preferably, the specific surface area of the tricobalt tetroxide is 1-5m ² /g;

Preferably, the tap density of the cobalt tetroxide is 2.6-3.0 g/cm ³ ;

Preferably, the median particle size of the cobalt tetroxide is 14-19 μm;

Preferably, the pore volume of the tricobalt tetroxide is 0.0010-0.0090 cm ³ /g.

3. according to claim 1 and 2 described three cobalt tetroxides, it is characterized in that, described three cobalt tetroxides comprise doping element, and described doping element is selected from one in Al, Mg, Ni, Mn, La, Zr, Ti, W or several;

Preferably, the doping mass contents of the doping elements are: Al: 0.40-1.20%, Mg: 0.08-0.50%, Ni: 0.10-3.00%, Mn: 0.10-3.00%, La: 0.05-0.30% , Zr: 0.10-0.30%, Ti: 0.05-0.30%, W: 0.10-0.50%;

Preferably, the pore volume of the tricobalt tetroxide is 0.0013-0.0020 cm ³ /g.

4. A cobalt carbonate, characterized in that, for the preparation of cobalt tetroxide described in any one of claims 1 to 3, the internal pore diameter of the cobalt carbonate is uniform, the pore distribution is uniform, and the pore volume of the cobalt carbonate is 0.01～0.10 cm ³ /g.

5. cobalt carbonate according to claim 4, is characterized in that, the aperture of described cobalt carbonate is 1.0～4.0nm;

Preferably, the specific surface area of the cobalt carbonate is 40-130m ² /g;

Preferably, the tap density of the cobalt carbonate is 1.4-2.0 g/cm ³ ;

Preferably, the median particle diameter of the cobalt carbonate is 16-22 μm.

6. A preparation method for cobalt carbonate, characterized in that, comprising:

The cobalt salt solution and the precipitant solution are added to the reaction kettle containing the bottom liquid for reaction, the flow rate of the cobalt salt solution increases with the increase of the particle size of the material, and the stirring speed of the reaction kettle increases with the increase of the particle size of the material. And reduce, continue to react to target particle size, obtain cobalt carbonate slurry;

The cobalt carbonate slurry is centrifugally washed to obtain the cobalt carbonate.

7. preparation method according to claim 6, is characterized in that, described cobalt salt solution is selected from cobalt sulfate solution and/or cobalt chloride solution; Described precipitation agent solution is selected from ammonium bicarbonate solution and/or sodium carbonate Solution, the bottom liquid is selected from ammonium bicarbonate solution and/or sodium carbonate solution;

Preferably, the cobalt concentration in the cobalt salt solution is 90-130g/L, the concentration of the precipitant solution is 190-230g/L; the concentration of the bottom solution is 5-50g/L;

Preferably, the cobalt salt solution includes a doping element selected from one or more of Al, Mg, Ni, Mn, La, Zr, Ti, W;

Preferably, the doping mass content of doping elements in the cobalt carbonate is respectively:

Al: 0.26-0.70%, Mg: 0.05-0.33%, Ni: 0.06-2.00%, Mn: 0.06-2.00%, La: 0.03-0.20%, Zr: 0.06-0.20%, Ti: 0.03-0.20%, W :0.06～0.33%.

8. The preparation method according to claim 6, wherein the flow range of the cobalt salt solution is 2 to 6%/h of the usable volume of the reactor, and the stirring speed range of the reactor is 300 to 100r/h. min;

Preferably, the target particle size of the cobalt carbonate is 16-22 μm.

9. A preparation method for tricobalt tetroxide, characterized in that, comprising:

The cobalt carbonate described in claim 4 or 5 is provided, or the cobalt carbonate prepared by the preparation method of cobalt carbonate described in any one of claims 6 to 8;

Sintering the cobalt carbonate to obtain tricobalt tetroxide;

Preferably, the sintering temperature is 700-850°C;

Preferably, before sintering the cobalt carbonate, it also includes preheating the cobalt carbonate, the preheating temperature is 200-500°C, and the preheating time is 20min-60min;

Preferably, when a rotary kiln is used for sintering, the rotation frequency of the rotary kiln tube is 0.5-1.5 r/min, and the material layer thickness is ≤16 cm.

10. A positive electrode material, characterized in that, lithium cobaltate obtained by calcining the cobalt tetroxide and lithium source according to any one of claims 1 to 3;

Preferably, the molar ratio of the lithium source to the tricobalt tetroxide is 1-1.05;

Preferably, the calcination temperature is 900-1200° C., and the calcination time is 20-30 hours.