Anion-doped cobaltosic oxide and preparation method and application thereof

Abstract

The application discloses anion-doped tricobalt tetraoxide as well as a preparation method and application thereof. The preparation method comprises the following steps: 1) mixing Al-doped cobalt oxide with a first fluorine source, and calcining to obtain surface layer F-doped cobalt oxide; and 2) using a second fluorine source, and using a gas phase coating method to perform F coating on the surface layer F-doped cobalt oxide to obtain anion-doped tricobalt tetraoxide. The method of the application performs Al doping in a bulk phase wet method, and combines surface layer F doping by a fire method and outer layer gas phase F coating, so that the stability and electrochemical performance of lithium cobaltate at high voltage can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and relates to anion-doped tricobalt tetraoxide and a preparation method and application thereof. BACKGROUND

[0002] To meet the rapidly developing market demand, the voltage of lithium cobaltate has been continuously broken through, and has been increased from 4.3V to 4.5V or even higher. The general direction of increasing the voltage of commercial lithium cobaltate is to perform Al doping in the wet synthesis precursor stage. The higher the Al doping amount, the more stable the structure, and the greater the voltage can be improved.

[0003] CN111115710A discloses a preparation method of aluminum-doped cobalt oxide. The method is to add a reaction bottom liquid to a reaction kettle and heat, then add an aluminum-containing cobalt salt solution, a sodium hydroxide solution and an oxidizing agent into the reaction bottom liquid in parallel flow, and control the pH value of the reaction system. Then, stirring is performed until the reaction is complete, to obtain aluminum-containing cobalt hydroxide slurry. Then, the aluminum-containing cobalt hydroxide slurry is sequentially subjected to aging, filtration, washing, drying and iron removal, to obtain aluminum-containing cobalt hydroxide powder. The aluminum-containing cobalt hydroxide powder is calcined according to a temperature curve, to obtain aluminum-doped cobalt oxide. In this way, by doping aluminum in cobalt oxide, the cost is reduced, and the cycle performance of cobalt oxide as a battery material is improved.

[0004] CN118183869A discloses aluminum-doped cobalt carbonate, aluminum-doped tricobalt tetraoxide and a preparation method and application thereof. An aluminum-doped cobalt hydroxide shell is formed on the aluminum-doped cobalt carbonate core by a cation-anion exchange method. Then, the aluminum-doped cobalt carbonate is sequentially subjected to low-temperature sintering and high-temperature sintering, to obtain aluminum-doped tricobalt tetraoxide.

[0005] However, when the Al doping amount is high, problems such as uneven distribution of Al and calcination cracking occur. At a higher voltage, the Al may react with the electrolyte, resulting in serious attenuation of the cycle capacity and thermal stability.

[0006] Therefore, it is a technical problem to be solved at present to provide tricobalt tetraoxide and a preparation method thereof, so that lithium cobaltate prepared by using the tricobalt tetraoxide has excellent high-voltage stability and electrochemical performance. SUMMARY

[0007] In view of the above technical problems in the prior art, the present application aims to provide anion-doped tricobalt tetraoxide and a preparation method and application thereof.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a preparation method of anion-doped tricobalt tetraoxide, characterized in that the preparation method comprises the following steps:

[0010] (1) mixing Al-doped cobalt oxide with a first fluorine source, calcining to obtain a surface layer F-doped cobalt oxide;

[0011] (2) using a second fluorine source, performing F-coating on the surface layer F-doped cobalt oxide by a gas phase coating method to obtain anion-doped tricobalt tetroxide.

[0012] The method of the present application uses Al-doped cobalt oxide, which can greatly improve the voltage platform of the material; by first performing F-doping by a pyrogenic method, on the one hand, the surface layer of the cobalt oxide is F-doped, achieving a synergistic effect of Al and F co-doping, on the other hand, a part of F will form a point-like coating on the surface of the material, and by using a gas phase coating method for F-coating, the point-like coating can be connected to form a continuous film, and the above factors together can protect the material from corrosion by the electrolyte at high voltage, improving the stability and electrochemical performance of the material. The lithium cobaltate prepared from the anion-doped tricobalt tetroxide prepared by the present application has excellent high-voltage stability and electrochemical performance.

[0013] At the same time, by using a pyrogenic method to dope F on the surface layer of the cobalt oxide, the problem of difficult treatment of wastewater caused by F-doping in the wet co-precipitation stage, and the problem of inaccurate F-doping amount in the positive electrode calcination stage can be perfectly solved.

[0014] The following is a preferred technical solution of the present application, but is not a limitation on the technical solutions provided by the present application. Through the following preferred technical solution, the technical purpose and beneficial effects of the present application can be better achieved and realized.

[0015] Preferably, the preparation method of the Al-doped cobalt oxide comprises the following steps:

[0016] (a) adding a cobalt-aluminum mixed solution and a precipitant solution into a bottom solution to perform a co-precipitation reaction to obtain an F-doped precursor;

[0017] (b) sintering the F-doped precursor to obtain Al-doped cobalt oxide.

[0018] The method of the present application uses a bulk wet doping method to dope Al, combined with surface layer pyrogenic F-doping and outer layer gas phase F-coating, which can improve the stability and electrochemical performance of lithium cobaltate at high voltage.

[0019] Preferably, the concentration of Co element in the cobalt-aluminum mixed solution in step (a) is 90-130 g / L, for example, it can be 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, 125 g / L or 130 g / L, etc.

[0020] Preferably, the Co element in the Co-Al mixed solution in step (a) is derived from at least one of CoCl2, CoSO4, and Co(NO3)2.

[0021] Preferably, the concentration of the Al element in the Co-Al mixed solution in step (a) is 0.1-2.5 g / L, such as 0.1 g / L, 0.15 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.45 g / L, 0.5 g / L, 0.6 g / L, 0.8 g / L, 1 g / L, 1.2 g / L, 1.3 g / L, 1.5 g / L, 1.7 g / L, 1.8 g / L, 2 g / L, 2.2 g / L, 2.3 g / L, 2.4 g / L, or 2.5 g / L, etc.

[0022] Preferably, the Al element in the Co-Al mixed solution in step (a) is derived from at least one of aluminum chloride, aluminum nitrate, aluminum sulfate, and aluminum acetate.

[0023] Preferably, the precipitant in the precipitant solution in step (a) comprises at least one of Na2CO3, NH4HCO3, and NaHCO3.

[0024] Preferably, the concentration of the precipitant solution in step (a) is 200-260 g / L, such as 200 g / L, 210 g / L, 220 g / L, 230 g / L, 240 g / L, 250 g / L, or 260 g / L, etc.

[0025] Preferably, the bottom liquid in step (a) is water or a precipitant solution, and the concentration of the bottom liquid is 0-50 g / L, such as 0, 0.1 g / L, 0.3 g / L, 0.5 g / L, 1 g / L, 3 g / L, 5 g / L, 7 g / L, 10 g / L, 12 g / L, 14 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, or 50 g / L, etc. When the concentration of the bottom liquid is 0, the bottom liquid is water; when the concentration of the bottom liquid is not 0, the bottom liquid is a precipitant solution.

[0026] Preferably, the pH of the co-precipitation reaction in step (a) is 7.0-7.6, such as 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, or 7.6, etc.

[0027] Preferably, the temperature of the co-precipitation reaction in step (a) is 40-60℃, such as 40℃, 42℃, 44℃, 45℃, 46℃, 48℃, 50℃, 52℃, 53℃, 55℃, 56℃, 58℃, or 60℃, etc.

[0028] In one embodiment, after the co-precipitation reaction in step (a) reaches the stop-pot particle size, washing and drying are performed.

[0029] Preferably, the sintering temperature of step (b) is 500-800℃, for example, it can be 500℃, 525℃, 550℃, 570℃, 580℃, 600℃, 625℃, 650℃, 660℃, 680℃, 700℃, 725℃, 750℃, 770℃, 780℃ or 800℃, etc.

[0030] As a preferred technical solution of the preparation method of the application, the first fluorine source of step (1) is ammonium fluoride. The application is beneficial to achieving uniform doping in the surface layer of the material by using volatile fluorine source for fire doping.

[0031] Preferably, the mass ratio of the Al-doped cobalt oxide to the first fluorine source in step (1) is 150-1100, for example, it can be 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050 or 1100, etc.

[0032] Preferably, the calcination temperature of step (1) is 250-450℃, for example, it can be 250℃, 260℃, 280℃, 300℃, 315℃, 330℃, 340℃, 350℃, 360℃, 380℃, 400℃, 410℃, 415℃, 430℃, 440℃ or 450℃, etc.

[0033] The method of the application can achieve fire doping of F at a lower temperature, and can dope F in the surface layer of the material to improve the performance of the material.

[0034] Preferably, the holding time of the calcination of step (1) is 2-6h, for example, it can be 2h, 2.5h, 3h, 4h, 5h or 6h, etc.

[0035] As a preferred technical solution of the preparation method of the application, the second fluorine source of step (2) is sodium fluorosilicate.

[0036] Preferably, in step (2), based on 3000g of the surface layer F-doped cobalt oxide, the amount of the second fluorine source is 2.4-15g, for example, 2.5g, 3g, 3.5g, 4g, 5g, 5.5g, 6g, 7g, 8g, 9g, 10g, 11g, 12g, 13g, 14g or 15g, etc.

[0037] Preferably, the heating temperature of the gas phase coating of step (2) is 350-450℃, for example, it can be 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃ or 450℃, etc.

[0038] Preferably, the method of the gas phase coating in step (2) is as follows: a partition is arranged in a closed container to divide the closed container into an upper part and a lower part, the surface layer F-doped cobalt oxide is placed on the upper part of the partition, a second fluorine source is placed below the partition, the second fluorine source is heated to generate fluorine-containing vapor, and the surface layer F-doped cobalt oxide is coated.

[0039] In one embodiment, the partition is a metal mesh, and the metal should not participate in chemical reactions.

[0040] In a second aspect, the present application provides an anion-doped tricobalt tetraoxide prepared by the method of the first aspect.

[0041] In a third aspect, the present application provides a positive electrode comprising the anion-doped tricobalt tetraoxide of the second aspect.

[0042] In a fourth aspect, the present application provides a battery comprising the positive electrode of the third aspect.

[0043] The numerical range of the present application includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed, and the present application does not exhaustively list the specific point values included in the range for the sake of brevity and simplicity.

[0044] Compared with the prior art, the present application has the following beneficial effects:

[0045] (1) The method of the present application uses Al-doped cobalt oxide, which can greatly improve the voltage platform of the material; by first performing a fire method to dope F, on the one hand, the surface layer of the cobalt oxide is F-doped, achieving a synergistic effect of Al and F co-doping, and on the other hand, a part of F will form a point-shaped coating on the surface of the material, and by using a gas phase coating method to dope F, the F coating can be connected with the point-shaped coating to form a continuous film, and the above factors work together to protect the material from corrosion by the electrolyte at high voltage, thereby improving the stability and electrochemical performance of the material.

[0046] (2) The anion-doped tricobalt tetraoxide prepared by the method of the present application has excellent high-voltage stability and electrochemical performance. The initial discharge capacity of lithium cobaltate prepared by the anion-doped tricobalt tetraoxide can reach 177 mAh / g or more at 1C rate, and the capacity retention rate can reach 85% or more after 100 cycles. DETAILED DESCRIPTION

[0047] The technical solutions of the present application will be further described below through specific embodiments.

[0048] Example 1

[0049] The embodiment provides a preparation method of anion-doped cobaltic tetraoxide, comprising the following steps:

[0050] Step one, a cobalt-aluminum mixed solution A (the concentration of Co element is 130 g / L, the Co element is derived from CoCl2, the concentration of Al element is 1.5 g / L, and the Al element is derived from aluminum acetate) and a precipitant solution B (NH4HCO3 solution, the concentration is 260 g / L) are configured;

[0051] Step two, 50 g / L of NH4HCO3 solution is added into a reaction kettle as a bottom solution, the cobalt-aluminum mixed solution A and the precipitant solution B are simultaneously pumped into the reaction kettle to perform a co-precipitation reaction, and the pH of the reaction system is controlled to be 7.6 and the temperature is controlled to be 60 DEG C in the process of the co-precipitation reaction.

[0052] Step three, after the reaction reaches a stop-kettle particle size, washing and drying are performed, and the obtained cobalt oxide is calcined at 800 DEG C to obtain the cobalt oxide.

[0053] Step four, the cobalt oxide obtained in step three is mixed with ammonium fluoride according to a mass ratio of 500, and the mixture is kept at 450 DEG C for 6 h to obtain the surface F-doped cobaltic tetraoxide.

[0054] Step five, a closed container with a horizontally arranged isolation piece is used, 3000 g of the surface F-doped cobaltic tetraoxide is placed above the isolation piece, 7.5 g of sodium fluosilicate is placed below the isolation piece, the sodium fluosilicate is heated to 450 DEG C to generate fluorine-containing steam, and the surface F-doped cobaltic tetraoxide is coated to obtain the anion-doped cobaltic tetraoxide.

[0055] Embodiment 2

[0056] The embodiment provides a preparation method of anion-doped cobaltic tetraoxide, comprising the following steps:

[0057] Step one, a cobalt-aluminum mixed solution A (the concentration of Co element is 130 g / L, the Co element is derived from CoCl2, the concentration of Al element is 1.5 g / L, and the Al element is derived from aluminum acetate) and a precipitant solution B (NH4HCO3 solution, the concentration is 260 g / L) are configured;

[0058] Step two, 50 g / L of NH4HCO3 solution is added into a reaction kettle as a bottom solution, the cobalt-aluminum mixed solution A and the precipitant solution B are simultaneously pumped into the reaction kettle to perform a co-precipitation reaction, and the pH of the reaction system is controlled to be 7.3 and the temperature is controlled to be 45 DEG C in the process of the co-precipitation reaction.

[0059] Step three, after the reaction reaches a stop-kettle particle size, washing and drying are performed, and the obtained cobalt oxide is calcined at 800 DEG C to obtain the cobalt oxide.

[0060] Step four, the cobalt oxide obtained in step three is mixed with ammonium fluoride according to a mass ratio of 1000, and is kept at 250℃ for 6h to obtain surface F-doped cobaltic oxide.

[0061] Step five, using a closed container with a horizontally arranged partition, 3000g of the surface F-doped cobaltic oxide is placed above the partition, 2.5g of sodium fluorosilicate is placed below the partition, the sodium fluorosilicate is heated to 400℃ to generate fluorine-containing steam, and the surface F-doped cobaltic oxide is coated to obtain anion-doped cobaltic oxide.

[0062] Example 3

[0063] The embodiment provides a preparation method of anion-doped cobaltic oxide, which comprises the following steps:

[0064] Step one, a cobalt-aluminum mixed solution A (wherein the concentration of Co element is 115g / L, the Co element is derived from CoSO4, and the concentration of Al element is 1.2g / L, the Al element is derived from aluminum acetate) and a precipitant solution B (a Na2CO3 solution with a concentration of 230g / L) are configured.

[0065] Step two, 30g / L of Na2CO3 solution is added into a reaction kettle as a bottom liquid, the cobalt-aluminum mixed solution A and the precipitant solution B are simultaneously pumped into the reaction kettle for co-precipitation reaction, and the pH of the reaction system is controlled to be 7.5 and the temperature is controlled to be 50℃ during the co-precipitation reaction.

[0066] Step three, after the reaction reaches a stop-pot particle size, washing and drying are performed, and the cobalt oxide is obtained by calcination at 650℃.

[0067] Step four, the cobalt oxide obtained in step three is mixed with ammonium fluoride according to a mass ratio of 200, and is kept at 350℃ for 4h to obtain surface F-doped cobaltic oxide.

[0068] Step five, using a closed container with a horizontally arranged partition, 3000g of the surface F-doped cobaltic oxide is placed above the partition, 15g of sodium fluorosilicate is placed below the partition, the sodium fluorosilicate is heated to 380℃ to generate fluorine-containing steam, and the surface F-doped cobaltic oxide is coated to obtain anion-doped cobaltic oxide.

[0069] Example 4

[0070] The embodiment provides a preparation method of anion-doped cobaltic oxide, which comprises the following steps:

[0071] Step one, configure a cobalt-aluminum mixed solution A (in which the concentration of Co element is 90 g / L, the Co element is derived from Co(NO3)2, and the concentration of Al element is 0.5 g / L, the Al element is derived from aluminum nitrate), a precipitant solution B (a NaHCO3 solution with a concentration of 240 g / L);

[0072] Step two, add water as a bottom liquid in a reaction kettle, pump the cobalt-aluminum mixed solution A and the precipitant solution B into the reaction kettle at the same time to perform a co-precipitation reaction, and control the pH of the reaction system to be 7.0 and the temperature to be 40℃ during the co-precipitation reaction.

[0073] Step three, after the reaction reaches a stop-kettle particle size, perform washing and drying, and then calcine at 700℃ to obtain cobalt oxide.

[0074] Step four, mix the cobalt oxide obtained in step three with ammonium fluoride according to a mass ratio of 650, and then heat at 300℃ for 5 h to obtain surface F-doped tricobalt tetroxide.

[0075] Step five, place 3000 g of surface F-doped tricobalt tetroxide on an isolation piece arranged horizontally in a closed container, place 10 g of sodium fluosilicate below the isolation piece, heat the sodium fluosilicate to 360℃ to generate fluorine-containing steam, and coat the surface F-doped tricobalt tetroxide to obtain anion-doped tricobalt tetroxide.

[0076] Example 5

[0077] The difference between this example and Example 1 is that the amount of sodium fluosilicate is 2.3 g.

[0078] Example 6

[0079] The difference between this example and Example 1 is that the amount of sodium fluosilicate is 15.1 g.

[0080] Comparative Example 1

[0081] This comparative example provides a tricobalt tetroxide material, which is different from Example 1 in that step four is not performed.

[0082] Comparative Example 2

[0083] This comparative example provides a tricobalt tetroxide material, which is different from Example 1 in that step five is not performed.

[0084] Comparative Example 3

[0085] This comparative example provides a tricobalt tetroxide material, which is different from Example 1 in that the cobalt-aluminum mixed solution A in step one is replaced by a CoCl2 solution, and the concentration of Co element in the CoCl2 solution is the same as that in Example 1.

[0086] Preparation of lithium cobalt oxide cathode material:

[0087] The anion-doped tricobalt tetraoxide prepared in Examples 1-6 and the tricobalt tetraoxide prepared in Comparative Examples 1-3 were used as precursor materials, and the molar ratio of lithium to cobalt (Li / Co) was 1.025, the precursor materials and lithium carbonate were weighed respectively, mixed and sintered in a box furnace, and sintered at 1100 DEG C in an air atmosphere for 9h; after sintering, the product was crushed, iron was removed, and sieved to obtain lithium cobalt oxide cathode material.

[0088] Performance test of lithium cobalt oxide cathode material:

[0089] Preparation of lithium ion battery:

[0090] The lithium cobalt oxide cathode material prepared by the above method was used as a positive active material, 80wt% of the positive active material, 10wt% of Super-P and 10wt% of polyvinylidene fluoride (PVDF) were dispersed in an N-methyl pyrrolidone (NMP) solution to prepare an electrode slurry, which was coated on an aluminum foil and dried to obtain a positive electrode;

[0091] Lithium sheet was used as a negative electrode;

[0092] The separator was a Φ19 PP microporous membrane (Celgard 2400);

[0093] The electrolyte was composed of 1M LiPF6 and a mixture of EC, DMC and EMC (EC: DMC: EMC volume ratio = 1:1:1).

[0094] The above positive electrode, separator, negative electrode and electrolyte were assembled to obtain a button cell.

[0095] The lithium cobalt oxide cathode material prepared by the tricobalt tetraoxide provided by Examples 1-6 and Comparative Examples 1-3 was used to assemble lithium ion batteries and perform performance tests, and the test conditions were: 1C cycle test under an electrochemical window of 3.0-4.6V, and the initial discharge capacity and capacity retention rate after 100 cycles were obtained. The test results are shown in Table 1.

[0096] Table 1

[0097]

[0098]

[0099] As shown in Table 1, the method of the present application uses a bulk wet doping method to dope Al, and combines surface layer F doping by fire method and outer layer F coating by gas phase, which can improve the stability and electrochemical performance of lithium cobalt oxide at high voltage.

[0100] Meanwhile, by comparing Example 1 with Examples 5-6, it can be seen that, within a certain range, a better electrical performance can be obtained by F-doping coating.

[0101] By comparing Example 1 with Comparative Example 1, it can be seen that, when no fluorine doping is performed externally and only chemical deposition is performed, the initial capacity and the cycle performance will decrease.

[0102] By comparing Example 1 with Comparative Example 2, it can be seen that, when only fluorine doping is performed externally and no chemical deposition is performed, the initial capacity decreases and the cycle performance decreases significantly.

[0103] By comparing Example 1 with Comparative Example 3, it can be seen that Al-doping affects the capacity of the material and cooperates with F to affect the initial capacity and the cycle performance.

[0104] The applicant declares that the detailed method of the present application is illustrated by the above examples, but the present application is not limited to the above detailed method, i.e. it does not mean that the present application must rely on the above detailed method to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of each raw material of the product of the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing an anion-doped tricobalt tetroxide, characterized by, The preparation method comprises the following steps: (1) mixing Al-doped cobalt oxide with a first fluorine source, calcining to obtain F-doped cobalt oxide on the surface; (2) using a second fluorine source, F-coating is performed on the F-doped cobalt oxide on the surface by a gas phase coating method to obtain anion-doped cobalt trioxide; In step (2), the second fluorine source is sodium fluorosilicate; In step (2), the gas phase coating method is as follows: an isolating piece is arranged in a closed container to divide the closed container into an upper part and a lower part, the F-doped cobalt oxide on the surface is placed on the upper part of the isolating piece, the second fluorine source is placed under the isolating piece, the second fluorine source is heated to generate fluorine-containing steam, and the F-doped cobalt oxide on the surface is coated.

2. The production method according to claim 1, characterized by, The preparation method of the Al-doped cobalt oxide comprises the following steps: (a) adding a cobalt-aluminum mixed solution and a precipitant solution into a bottom liquid to perform a coprecipitation reaction to obtain an F-doped precursor; (b) sintering the F-doped precursor to obtain Al-doped cobalt oxide.

3. The production method according to claim 2, characterized by, In step (a), the concentration of Co elements in the cobalt-aluminum mixed solution is 90-130 g / L.

4. The production method according to claim 2, characterized by, In step (a), the Co elements in the cobalt-aluminum mixed solution are derived from at least one of CoCl2, CoSO4 and Co(NO3)2.

5. The preparation method according to claim 2, characterized in that, In step (a), the concentration of Al elements in the cobalt-aluminum mixed solution is 0.1-2.5 g / L.

6. The preparation method according to claim 2, characterized in that, In step (a), the Al elements in the cobalt-aluminum mixed solution are derived from at least one of aluminum chloride, aluminum nitrate, aluminum sulfate and aluminum acetate.

7. The preparation method according to claim 2, characterized in that, In step (a), the precipitant in the precipitant solution comprises at least one of Na2CO3, NH4HCO3 and NaHCO3.

8. The preparation method according to claim 2, characterized in that, In step (a), the concentration of the precipitant solution is 200-260 g / L.

9. The preparation method according to claim 2, characterized in that, In step (a), the bottom liquid is water or a precipitant solution, and the concentration of the bottom liquid is 0-50 g / L.

10. The method of claim 2, wherein, In step (a), the pH of the coprecipitation reaction is 7.0-7.

6.

11. The method of claim 2, wherein, In step (a), the temperature of the coprecipitation reaction is 40-60 ℃.

12. The method of claim 2, wherein, In step (b), the sintering temperature is 500-800 ℃.

13. The method of claim 1, wherein, In step (1), the first fluorine source is ammonium fluoride.

14. The method of claim 1, wherein, In step (1), the mass ratio of the Al-doped cobalt oxide to the first fluorine source is 150-1100.

15. The method of claim 1, wherein, In step (1), the calcining temperature is 250-450 ℃.

16. The method of claim 1, wherein, In step (1), the holding time of the calcining is 2-6 h.

17. The method of claim 1, wherein, In step (2), based on 3000 g of the F-doped cobalt oxide on the surface, the amount of the second fluorine source is 2.4-15 g.

18. The method of claim 1, wherein, In step (2), the heating temperature of the gas phase coating is 350-450 ℃.

19. An anion-doped tricobalt tetroxide characterized in that, The anion-doped cobalt trioxide is prepared by the method in any one of claims 1-18.

20. A positive electrode, comprising: The positive electrode comprises the anion-doped cobalt trioxide in claim 19.

21. A battery, characterized by The battery comprises the positive electrode in claim 20.

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