WO2022127129A1

WO2022127129A1 - Doped cobaltosic oxide and preparation method therefor

Info

Publication number: WO2022127129A1
Application number: PCT/CN2021/109819
Authority: WO
Inventors: 胡进; 陈九华; 杨志
Original assignee: 巴斯夫杉杉电池材料有限公司
Priority date: 2020-12-18
Filing date: 2021-07-30
Publication date: 2022-06-23
Also published as: CN112760710A

Abstract

A doped cobaltosic oxide. The morphology of the doped cobaltosic oxide is a single-crystal particle or a single-crystal-like aggregate, the primary grain size is 200-500 nm, and the half-peak width of a 311 crystal face is 0.2-0.6. The preparation method comprises: adjusting the pH value of a reaction kettle base solution to be 7.1±0.05; adding a mixed salt solution containing cobalt and doped elements and an ammonium bicarbonate solution into a reaction kettle for reaction, and controlling the pH value of a reaction system to be 7.1±0.05; standing and clarifying a slurry overflowing from the full liquid level of the reaction kettle, removing a supernatant, controlling the solid content of the slurry, returning the slurry to the reaction kettle for reaction, and stopping feeding until the reaction reaches the target particle size; and washing, drying, sieving and calcining the obtained material to obtain the doped cobaltosic oxide. The obtained doped cobaltosic oxide has a monocrystal or monocrystal-like aggregate morphology, and the compaction density is high.

Description

A kind of doped cobalt tetroxide and preparation method thereof

technical field

The invention belongs to the field of lithium ion battery materials, in particular to a doped cobalt tetroxide and a preparation method thereof.

Background technique

With the iterative upgrade of products in the digital field and the rapid development of various high-end model aircraft, drones and other emerging electronic products, the requirements for the lightweight and battery capacity of lithium batteries are getting higher and higher. Lithium cobalt oxide cathode materials have an important application direction in the digital field. As electronic products have increasingly strict performance requirements for lithium batteries, the update iteration of lithium cobalt oxide cathode materials is particularly important. The performance of the lithium cobalt oxide cathode material depends largely on the performance of the precursor. At present, in order to prepare high energy density cathode materials, on the one hand, the voltage platform of the cathode material is improved through doping technology, and on the other hand, the cathode material is improved through the matching technology of large and small particles. The compacted density of the material. The lithium cobalt oxide cathode material is mainly prepared by calcining cobalt tetroxide and lithium carbonate at a certain temperature. With the in-depth research of doping technology and particle matching technology, the technical modification of lithium cobalt oxide cathode material is gradually studied by sintering modification. Turning to the research on the synthesis process and performance of the precursor of cobalt tetroxide, it is of great significance to deepen the research of cobalt tetroxide to improve the performance of lithium cobalt oxide.

The preparation methods of cobalt tetroxide include spray pyrolysis, liquid-phase precipitation-thermal decomposition method, etc. The cobalt tetroxide prepared by liquid-phase precipitation-thermal decomposition method mainly adopts batch process to synthesize cobalt carbonate first, and then prepare porous cobalt tetroxide through thermal decomposition. For example, the preparation method of dense crystal small particle spherical cobalt carbonate mentioned in Chinese patent CN2020100308075, and the preparation method of cobalt tetroxide mentioned in Chinese patent CN106882843A, the particle size of the prepared cobalt carbonate is relatively large, and the secondary particle morphology is not easy to sinter into a single crystal. At present, the preparation technology of single crystal cobalt tetroxide is generally prepared by spray pyrolysis. The spray pyrolysis method mainly obtains single crystal cobalt tetroxide from cobalt chloride solution through pyrolysis, but this method will lead to the generation of a large amount of hydrogen chloride gas, and the treatment of exhaust gas is strict, and The spray pyrolysis method cannot be applied to the preparation of doped single crystal cobalt tetroxide.

At present, lithium cobalt oxide cathode materials are mostly made of polycrystalline small particles of conventional secondary spherical particles of tricobalt tetroxide as raw materials, but there are relatively high pores inside the raw materials of polycrystalline small particles, and due to the small particle size, cobalt and doping elements are in the sintering process. It is easy to form a state of phase separation, which makes the distribution of doping elements uneven, and the positive electrode materials prepared by using polycrystalline agglomerates have low compaction density and serious battery gas production.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology, and provide a doped type cobalt tetroxide and a preparation method thereof.

In order to solve the above-mentioned technical problems, the technical scheme proposed by the present invention is:

A doped cobalt tetroxide, the morphology of the doped cobalt tetroxide is a single crystal particle or a quasi-single crystal agglomerate, the primary grain size of the doped cobalt tetroxide is 200-500nm, and the half-peak width of the 311 crystal plane is is 0.2-0.6.

For the above-mentioned doped cobalt tetroxide, preferably, the particle size of the doped cobalt tetroxide is D ₁₀ ≥1 μm, D ₅₀ =2-6 μm, D ₉₀ ≤10 μm, and particle size distribution (D ₉₀ -D ₁₀ )/D ₅₀ ≤1.1 .

The above-mentioned doped tricobalt tetroxide, preferably, the specific surface area BET of the doped tricobalt tetroxide satisfies the relational expression 0.5≤(BET-2.5)/(TD-1.5)≤1, wherein, the tap density TD≥1.5g/cm ^3. The bulk density is greater than or equal to 1.1g/cm ³ .

The above-mentioned doped cobalt tetroxide, preferably, the molecular formula of the doped cobalt tetroxide is Co _x A _ly M _z O ₄ , wherein M is selected from Mg, Ti, Zr, Nb, La, Y, Ni or Mn. At least one, 2≤x≤3, 0<y≤0.5, 0≤z≤0.5, 8x+9y+6z=24.

As a general inventive concept, the present invention also provides a preparation method of the above-mentioned doped cobalt tetroxide, comprising the following steps:

(1) According to the stoichiometric ratio, prepare a soluble mixed salt solution and an ammonium bicarbonate solution, and the soluble mixed salt solution refers to a mixed solution of a soluble cobalt salt and a soluble doped element salt;

(2) add pure water as bottom liquid in the reactor, adjust the pH=7.1±0.05 of bottom liquid;

(3) adopting the mode of co-current addition, adding the soluble mixed salt solution and the ammonium bicarbonate solution to the reaction kettle simultaneously for reaction, and controlling the pH of the reaction system in the reaction process to be 7.1 ± 0.05;

(4) The slurry overflowing from the full liquid level of the reactor is allowed to stand for clarification, the supernatant is removed, the solid content of the slurry is controlled, and the slurry is returned to the reactor for reaction until the reaction reaches the target particle size stop feeding;

(5) washing, drying, sieving and calcining the material obtained after the reaction in step (4) to obtain doped cobalt tetroxide.

In the preparation process, the growth rate of the particles is accelerated by controlling a low and constant pH value. At a relatively fast growth rate, controlling the high rotation speed can effectively promote the dispersion of the particles, prevent agglomeration, and make the co-precipitation of doping elements. The effect is more even. In the prior art, a relatively high pH value is usually used, the purpose of which is to control a lower growth rate and prevent agglomeration, but the applicant found through research that the growth rate is too slow, which is not conducive to achieving uniform doping of aluminum, and During the co-precipitation process, the change of pH value will also destroy the uniformity of element doping; therefore, the present invention controls the pH value to be very low and constant, and simultaneously adopts high rotational speed, low temperature and low pH Value combination, that is, using high speed to solve the problem of easy agglomeration of particles during growth, using lower temperature control to provide a suitable nucleation speed, and under the premise that agglomeration does not occur during the co-precipitation reaction, the morphology can be obtained. Preferably, small-grain doped single crystal or quasi-single crystal cobalt tetroxide with relatively uniform aluminum doping.

In the above preparation method, preferably, in step (4), the solid content of the slurry is controlled to be 40-50%, and the target particle size of the slurry in the reaction kettle is 2-4 μm.

In the above preparation method, preferably, in step (3), the temperature of the reaction process is 40-50° C., and the stirring speed of the reactor stirrer is 800-1000 rpm. Further preferably, the temperature of the reaction process is 40-45° C., and the rotating speed of the reactor stirrer is 800-850 rpm.

In the above preparation method, preferably, in step (1), the concentration of the soluble mixed salt solution is 100-140g/L, and the concentration of ammonium bicarbonate is 200-240g/L;

In step (3), the flow rate that the soluble mixed salt solution passes into the reactor is 80-100 mL/min. Further preferably, the flow rate of the mixed salt solution is 85±5ml/min.

In the above-mentioned preparation method, preferably, in step (5), washing means that the material is washed alternately with hot pure water and ammonium bicarbonate solution, the hot water temperature is 70-80 ° C, and the concentration of ammonium bicarbonate solution is 80-120 g/L ; The drying temperature is 100-120℃.

In the above preparation method, preferably, in step (5), calcining refers to sintering at a constant temperature of 350°C for 2-3 hours, and then sintering at 900-950°C for 3-9 hours; the calcination process is carried out in an air atmosphere, and the gas The flow rate is 10-15L/h.

Compared with the prior art, the advantages of the present invention are:

(1) The doped tricobalt tetroxide of the present invention has a single crystal or quasi-single crystal agglomerate morphology. Compared with the conventional secondary agglomerate morphology, its compaction density is significantly higher, which is a good way to synthesize high-energy-density cobalt tetroxide. Lithium cobalt oxide cathode material provides assurance.

(2) In the preparation method of the present invention, by controlling a low and constant pH value, the growth rate of the particles is accelerated, and at a relatively fast growth rate, controlling the high rotation speed can effectively promote the dispersion of the particles, prevent agglomeration, and make The co-precipitation effect of doping elements is more uniform, and small-grain doped single crystal or quasi-single crystal cobalt tetroxide with better morphology and more uniform Al doping can be obtained.

(3) The preparation method of the present invention, by adopting the technological characteristics of high rotational speed and slurry recycling, makes the cobalt carbonate crystal nucleus generated in the wet synthesis process smaller, the semi-finished cobalt tetroxide particle size smaller, and the morphology uniformity better, The particles are more compact.

(4) The preparation method of the present invention makes cobalt carbonate better fuse with aluminum during the sintering process by sintering at high temperature, and it is easier to form a flaky segregation morphology than cobalt tetroxide doped aluminum in the secondary spherical particles, and the present invention There is no segregation of Al in the single crystal or quasi-single crystal cobalt tetroxide. Combined with the co-precipitation process and sintering technology, the doped Al element is easier to be doped into the cobalt tetroxide lattice.

Description of drawings

FIG. 1 is a schematic diagram of the doped cobalt carbonate particles obtained in Example 1 of the present invention under a 50,000-fold electron microscope.

2 is a particle size distribution diagram of the doped cobalt tetroxide obtained in Example 1 of the present invention.

3 is a schematic diagram of the doped cobalt tetroxide particles obtained in Example 1 of the present invention under a 50,000-fold electron microscope.

4 is a schematic diagram of the doped cobalt tetroxide particles obtained in Example 1 of the present invention under a 20,000-fold electron microscope.

5 is a schematic diagram of the doped cobalt tetroxide particles obtained in Example 1 of the present invention under a 10,000-fold electron microscope.

6 is a schematic cross-sectional view of the doped cobalt tetroxide particles prepared in Example 1 of the present invention.

FIG. 7 is a distribution diagram of the element uniformity of the cross-section of the doped cobalt tetroxide prepared in Example 1 of the present invention.

8 is an analysis diagram of the phase structure of the doped cobalt tetroxide particles prepared in Example 1 of the present invention.

9 is a schematic diagram of the doped cobalt carbonate particles obtained in Example 2 of the present invention under a 50,000-fold electron microscope.

10 is a particle size distribution diagram of the doped cobalt tetroxide obtained in Example 2 of the present invention.

11 is a schematic diagram of the doped cobalt tetroxide particles obtained in Example 2 of the present invention under a 50,000-fold electron microscope.

12 is a schematic diagram of the doped cobalt tetroxide particles obtained in Example 2 of the present invention under a 30,000-fold electron microscope.

13 is a schematic diagram of the doped cobalt tetroxide particles obtained in Example 2 of the present invention under a 10,000-fold electron microscope.

14 is a schematic cross-sectional view of the doped cobalt tetroxide particles prepared in Example 2 of the present invention.

15 is a distribution diagram of the element uniformity of the cross-section of the doped cobalt tetroxide prepared in Example 2 of the present invention.

16 is an analysis diagram of the phase structure of the doped cobalt tetroxide particles prepared in Example 2 of the present invention.

17 is a schematic diagram of the cobalt carbonate particles obtained in Comparative Example 1 of the present invention under a 50,000-fold electron microscope.

Fig. 18 is a particle size distribution diagram of cobalt tetroxide obtained in Comparative Example 1 of the present invention.

19 is a schematic diagram of the cobalt tetroxide particles obtained in Comparative Example 1 of the present invention under a 50,000-fold electron microscope.

20 is a schematic diagram of the cobalt tetroxide particles obtained in Comparative Example 1 of the present invention under a 30,000-fold electron microscope.

21 is a schematic diagram of the cobalt tetroxide particles obtained in Comparative Example 1 of the present invention under a 10,000-fold electron microscope.

22 is a schematic cross-sectional view of the cobalt tetroxide particles prepared in Comparative Example 1 of the present invention.

FIG. 23 is a distribution diagram of element uniformity in the cross-section of cobalt tetroxide prepared in Comparative Example 1 of the present invention.

24 is an analysis diagram of the phase structure of cobalt tetroxide particles prepared in Comparative Example 1 of the present invention.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described more comprehensively and in detail below with reference to the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

Example 1:

A doped type cobalt tetroxide precursor of the present invention, the molecular formula is Co _2.97 Al _0.027 O ₄ , the morphology is a single crystal particle, the primary grain size is 400nm, the half-peak width of the 311 crystal plane is 0.25, and the particle size of the doped type cobalt tetroxide is D ₁₀ =2.72 μm, D ₅₀ =4.52 μm, D ₉₀ =6.73 μm; particle size distribution (D ₉₀ -D ₁₀ )/D ₅₀ =0.88, tap density TD=1.77 g/cm ³ , bulk density=1.25 g /cm ³ , (BET-2.5)/(TD-1.5)=0.91.

The preparation method of the doped cobalt tetroxide precursor in this embodiment includes the following steps:

(1) according to the stoichiometric ratio of Co _2.97 Al _0.027 O ₄ to prepare a soluble mixed salt solution with a total concentration of metal ions (aluminum ions and cobalt ions) of 110 g/l;

(2) in 50L reactor, add 10L pure water as reactor bottom liquid, pump a certain amount of ammonium bicarbonate solution into the reactor bottom liquid, and adjust the pH value of bottom liquid to be 7.1;

(3) open the stirring device of the reactor, the rotating speed is controlled at 800rpm, the temperature of the reactor is controlled at 45 ℃, then 220g/L ammonium bicarbonate solution, 110g/L mixed salt solution are pumped into the reactor simultaneously to react, the mixed salt solution The flow rate of ammonium bicarbonate is 85mL/min, and the flow rate of ammonium bicarbonate is adjusted with the constant pH=7.1;

(4) As the feeding continues, after the liquid level of the reactor is full, let the overflowed slurry stand for 20 minutes, remove part of the supernatant at the same time, control the solid content of the slurry at 40%, and return the slurry In the reactor, repeat this step once every 1 hour;

(5) After the reaction reaches the target particle size D50=2.5μm, stop feeding, discharge the slurry from the overflow port at the bottom of the reactor, and mix the collected material with the overflow material, pass through a centrifuge and use pure water and Ammonium bicarbonate was alternately washed, the temperature of pure water was controlled at 70°C, and the concentration of ammonium bicarbonate was controlled at 110g/l, until the pH of the washing water was less than 8; When the moisture content of the material is less than 10%, the dried material is screened by a 325-mesh screen to obtain a screened material; the photo of the screened material under a 50,000 times electron microscope is shown in Figure 1;

(6) calcining the sieved material obtained in step (5) in an air atmosphere (gas flow rate 12 L/h), first at 350° C. for 3 hours, and then at 950° C. for 4 hours, and the obtained powder is sieved to obtain Doped cobalt tetroxide, sealed and preserved.

The SEM images of the doped cobalt tetroxide prepared in this example are shown in Figures 3-5. It can be seen from the figures that the doped cobalt tetroxide has a single crystal morphology, the primary particle size is 400 nm, and the secondary particle size D ₁₀ =2.72 μm , D ₅₀ =4.52 μm, D ₉₀ =6.73 μm; particle size distribution (D ₉₀ -D ₁₀ )/D ₅₀ =0.88 (see the particle size analysis in Figure 2 ), the tap density is 1.77 g/cm ³ , and the specific surface area is 2.7 m ² /g, and the bulk density was 1.25 g/cm ³ .

The cross-sectional schematic diagram of the doped cobalt tetroxide prepared in this example is shown in FIG. 6 , and the element uniformity distribution diagram of the cross-sectional schematic diagram is shown in FIG. 7 . It can be seen from the figure that the distribution of aluminum elements doped with the precursor is relatively uniform.

The XRD pattern of the doped cobalt tetroxide prepared in this example is shown in FIG. 8 , and it can be seen from the figure that the half width of the 311 crystal plane of the precursor is 0.25.

Example 2:

A doped type of cobalt tetroxide of the present invention, the molecular formula is Co _2.97 Al _0.02 Mg _0.01 O ₄ , the morphology is a quasi-single crystal agglomerate, the primary grain size is 300nm, the half-peak width of the 311 crystal plane is 0.3, and the doped type The particle size of cobalt tetroxide is D ₁₀ =2.22μm, D ₅₀ =4.3μm, D ₉₀ =6.42μm; particle size distribution (D ₉₀ -D ₁₀ )/D ₅₀ =0.97, tap density TD=2.05g/cm ³ , loose packing Density=1.25g/ ^cm3 , (BET-2.5)/(TD-1.5)=0.73.

The preparation method of the doped cobalt tetroxide in this embodiment includes the following steps:

(1) According to the stoichiometric ratio of Co _2.97 Al _0.02 Mg _0.01 O ₄ , prepare a soluble mixed salt solution with a total concentration of metal ions (cobalt ions and doped metal ions) of 110 g/l;

(3) open the stirring device of the reactor, the rotating speed is controlled at 900rpm, and the temperature of the reactor is controlled at 45 ℃, and then the mixed salt solution of 230g/l ammonium bicarbonate and 110g/l is simultaneously pumped into the reactor to react, and the mixed salt solution The flow rate of ammonium bicarbonate is 90ml/min, and the flow rate of ammonium bicarbonate is adjusted with the constant pH=7.15;

(4) As the feeding continues, let the overflowed slurry stand for 20 minutes, remove part of the supernatant at the same time, control the solid content of the slurry to be 45%, and return the slurry to the reactor; this process Repeat every 1 hour;

(5) After the reaction reaches the target particle size D50 = 2.5 μm, the slurry is discharged from the overflow port at the bottom of the reactor. After the collected material is mixed with the overflow material, it is passed through a centrifuge using pure water and ammonium bicarbonate. Alternate washing, the temperature of pure water is controlled at 70 °C, and the concentration of ammonium bicarbonate is controlled at 110 g/l, until the pH of the washing water is less than 8;

(6) drying the washing material obtained in step (5) through a hot air oven (drying temperature is 110° C.), controlling the moisture content of the dried material to be less than 10%, and sieving the dried material through a 325 mesh screen to obtain a screening material; the photo of the sieved material under the electron microscope at 50,000 times is shown in Figure 9;

(7) calcining the sieved material in an air atmosphere (gas flow rate 12L/h), first calcining at 350°C for 3 hours, and then calcining at 950°C for 4 hours, the obtained powder is sieved to obtain doped cobalt tetroxide, sealed save.

The SEM images of the doped cobalt tetroxide prepared in this example are shown in Figures 11-13. It can be seen from the figures that the morphology of the doped cobalt tetroxide is quasi-single crystal, the primary particle size is 300 nm, and the secondary particle size D ₁₀ =2.22 μm, D ₅₀ =4.3 μm, D ₉₀ =6.42 μm; particle size distribution (D ₉₀ -D ₁₀ )/D ₅₀ =0.97 (see the particle size analysis in Fig. 10 ), the tap density is 2.05 g/cm ³ , and the specific surface area is 2.9m ² /g, and the bulk density is 1.25g/cm ³ .

14 is a schematic cross-sectional view of the doped cobalt tetroxide prepared in this example, FIG. 15 is an element uniformity distribution diagram of the doped cobalt tetroxide prepared in this example, and FIG. 16 is an XRD pattern of the doped cobalt tetroxide prepared in this example. , it can be seen that its 311 crystal plane half width is 0.3.

Comparative Example 1:

The molecular formula of the doped cobalt tetroxide of this comparative example is Co _2.97 Al _0.03 O ₄ .

The preparation method of the cobalt tetroxide of this comparative example comprises the following steps:

(1) according to the stoichiometric ratio of the molecular formula, prepare a soluble mixed salt solution with a total concentration of 110 g/L of metal ions (cobalt ions and aluminum ions);

(2) in 50L reactor, add 10L pure water as reactor bottom liquid, add 5L ammonium bicarbonate simultaneously;

(3) open the stirring device of the reactor, the rotating speed is controlled at 800rpm, and the temperature of the reactor is controlled at 45 ℃, then the ammonium bicarbonate of 220g/L and the mixed salt solution are added simultaneously in the reactor to react, and the flow of the mixed salt solution is 86mL /min, the flow rate of ammonium bicarbonate is 95mL/min;

(4) as the reaction proceeds, when the liquid level is full of the kettle, stop feeding, let stand, and after the reactor is clarified, pump the supernatant, and then return to the reactor again;

(5) Repeat step (4) until the reaction reaches the target particle size D50=3.5 μm, discharge the slurry from the overflow port at the bottom of the reactor, and the collected material is washed alternately with pure water and ammonium bicarbonate through a centrifuge, and the pure The water temperature is controlled at 70℃, and the concentration of ammonium bicarbonate is controlled at 110g/L until the pH of the washing water is less than 8;

(6) drying the washing material obtained in step (5) through a hot air oven, the drying temperature is 110° C., the moisture content of the dried material is less than 10%, and the dried material is sieved through a 325-mesh screen to obtain a sieved material ; The photo of the screening material under the electron microscope at 50,000 times is shown in Figure 17;

(7) calcining the sieved material in an air atmosphere (gas flow rate 12L/h), first calcining at 350°C for 3 hours, and then calcining at 950°C for 4 hours, the obtained powder is sieved to obtain cobalt tetroxide, which is sealed and stored.

The SEM images of the cobalt tetroxide prepared in this comparative example are shown in Figures 19-21. It can be seen from the figures that the doped cobalt tetroxide has a polycrystalline structure, the primary particle size is 200 nm, and the secondary particle size of the doped cobalt tetroxide D ₁₀ =2.54 μm, D ₅₀ =5.06 μm, D ₉₀ =10.37 μm; particle size distribution (D ₉₀ -D ₁₀ )/D ₅₀ =1.54 (see the particle size analysis in Figure 18 ), the tap density of the cobalt tetroxide is 1.77 g/cm ³ , The specific surface area was 5.2 m ² /g, and the bulk density was 1.25 g/cm ³ .

The cross-sectional schematic diagram of the doped cobalt tetroxide prepared in this comparative example is shown in Figure 22, and the element uniformity distribution diagram is shown in Figure 23. It can be seen from the figure that the distribution uniformity of the aluminum element doped by the precursor is obviously inferior to that of Example 1. , which is due to the difference in the particle size of cobalt carbonate and the difference in the morphology of cobalt carbonate leading to the difference in cobalt tetroxide.

The XRD schematic diagram of the doped cobalt tetroxide prepared in this comparative example is shown in Figure 24, and it can be seen from the figure that the half-peak width of the 311 crystal plane is 0.25.

Claims

A doped cobalt tetroxide, characterized in that the morphology of the doped cobalt tetroxide is a single crystal particle or a quasi-single crystal agglomerate, and the primary grain size of the doped cobalt tetroxide is 200-500 nm, 311 crystals The half-width of the plane is 0.2-0.6.
The doped cobalt tetroxide according to claim 1, wherein the particle size of the doped cobalt tetroxide is D 10 ≥ 1 μm, D 50 =2-6 μm, D 90 ≤10 μm, and the particle size distribution is (D 90 -D 10 ) )/D 50 ≤1.1.
The doped cobalt tetroxide according to claim 1, wherein the specific surface area BET of the doped cobalt tetroxide satisfies the relational expression 0.5≤(BET-2.5)/(TD-1.5)≤1, wherein the tap density TD≥1.5g/cm 3 , bulk density≥1.1g/cm 3 .
The doped cobalt tetroxide according to any one of claims 1-3, wherein the molecular formula of the doped cobalt tetroxide is Co x A ly M z O 4 , wherein M is selected from Mg, Ti, Zr , at least one of Nb, La, Y, Ni or Mn, 2≤x≤3, 0<y≤0.5, 0≤z≤0.5, 8x+9y+6z=24.
A preparation method of doped cobalt tetroxide according to any one of claims 1-4, characterized in that, comprising the following steps:

(1) Prepare a soluble mixed salt solution according to a stoichiometric ratio, and the soluble mixed salt solution refers to a mixed solution of a soluble cobalt salt and a soluble doping element salt;

Prepare ammonium bicarbonate solution;

(2) add pure water as bottom liquid in the reactor, adjust the pH=7.1 ± 0.05 of bottom liquid;

(3) adopting the mode of co-current addition, adding the soluble mixed salt solution and the ammonium bicarbonate solution to the reaction kettle simultaneously for reaction, and controlling the pH of the reaction system in the reaction process to be 7.1 ± 0.05;

(4) The slurry overflowing from the full liquid level of the reactor is allowed to stand for clarification, the supernatant is removed, the solid content of the slurry is controlled, and the slurry is returned to the reactor for reaction until the reaction reaches the target particle size stop feeding;

(5) washing, drying, sieving and calcining the material obtained after the reaction in step (4) to obtain doped cobalt tetroxide.
The preparation method according to claim 5, characterized in that, in step (4), the solid content of the slurry is controlled to be 40-50%, and the target particle size of the slurry in the reactor is 2-4 μm.
The preparation method according to claim 5, characterized in that, in step (3), the temperature of the reaction kettle is 40-50 DEG C, and the stirring speed of the agitator of the reaction kettle is 800-1000rpm.
The preparation method of claim 5, wherein in step (1), the concentration of the soluble mixed salt solution is 100-140g/L, and the concentration of ammonium bicarbonate is 200-240g/L;

In step (3), the flow rate that the soluble mixed salt solution passes into the reactor is 80-100 mL/min.
The preparation method according to any one of claims 5-8, characterized in that, in step (5), washing means that the material is washed alternately with hot pure water and ammonium bicarbonate solution, and the hot water temperature is 70-80° C. , the concentration of ammonium bicarbonate solution is 80-120g/L; the drying temperature is 100-120℃.
The preparation method according to any one of claims 5-8, characterized in that, in step (5), calcining refers to constant temperature sintering at 350°C for 2-3 hours, and then sintering at 900-950°C for 3-3 hours. 9 hours; the calcination process is carried out in an air atmosphere, and the gas flow rate is 10-15L/h.