Aluminum-doped lithium cobalt oxide precursor as well as preparation method and application thereof

Abstract

The invention provides an aluminum-doped lithium cobalt oxide precursor and a preparation method and application thereof, and the preparation method comprises the following steps: (1) a nucleation stage: adding a cobalt chloride solution, an aluminum salt solution and a precipitant solution into a reaction base solution, and carrying out first coprecipitation to obtain a solution containing an inner core; (2) growth stage: adding a cobaltous sulfate solution, an aluminum salt solution and a precipitant solution into the solution containing the inner core obtained in the step (1), and carrying out second coprecipitation to obtain a solution containing precipitates; and (3) final stage: adding a solution containing cobalt chloride and cobalt sulfate, an aluminum salt solution and a precipitator solution into the solution containing the precipitate obtained in the step (2), carrying out third coprecipitation, and carrying out heat treatment to obtain the aluminum-doped lithium cobalt oxide precursor. According to the preparation method, the problems of particle cracking and small particle explosion of aluminum-doped cobaltosic oxide under the condition of high aluminum doping amount can be avoided, and a lithium cobalt oxide battery prepared from the obtained aluminum-doped lithium cobalt oxide precursor shows excellent electrochemical performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium cobalt oxide batteries and relates to an aluminum-doped lithium cobalt oxide precursor, and in particular to an aluminum-doped lithium cobalt oxide precursor and a preparation method and application thereof. Background Art

[0002] With the rapid development of 3C electronic devices, the energy density requirements for lithium cobalt oxide (LiCoO2, LCO) batteries are constantly increasing. One of the common strategies to increase capacity is to dope to stabilize the material structure and thus expand its upper limit of operating voltage. Aluminum (Al) is a doping element widely used in industry to modify LCO. A large number of studies have shown that Al doping has the following significant advantages: First, Al is not electrochemically active within the electrochemical window of LCO and is a stable dopant that can effectively improve the thermal stability and cycle performance of the material; secondly, Al3+ (ion radius of about 53.5pm) and Co3 + (ion radius is about 54.5pm) with similar radius, it is easy to incorporate into the lattice without significantly changing the lattice structure; secondly, aluminum is the third most abundant element in the earth's crust, with abundant reserves and low cost; thirdly, the strength of the Al-O bond is higher than that of the Co-O bond. During the high-voltage charge and discharge process of LCO, Al doping can inhibit the excessive expansion of the lattice parameters and effectively stabilize the structure, thereby improving the structural stability of the material at high operating voltage, thereby increasing the operating voltage of the battery.

[0003] However, as a precursor of lithium cobalt oxide, when the Al doping of conventional single-morphology aluminum-doped cobalt tetroxide reaches a certain value, excessive aluminum doping during the preparation of aluminum-doped cobalt tetroxide will lead to local segregation of Al, resulting in problems such as cracking of aluminum-doped cobalt tetroxide particles and explosion of small particles, resulting in the deterioration of the performance of the prepared aluminum-doped lithium cobalt oxide precursor, which is far from achieving the expected effect.

[0004] CN118811867A discloses a lithium cobalt oxide cathode material precursor, its preparation, cathode materials, and applications. The precursor comprises aluminum-doped, phosphorus-coated cobalt oxide. The lithium cobalt oxide cathode material precursor provided in this document is aluminum-doped, phosphorus-coated cobalt oxide formed by calcining cobalt carbonate.

[0005] CN114180644A discloses an aluminum-doped cobalt carbonate material, its preparation method, aluminum-doped cobalt tetroxide, and lithium cobaltate positive electrode materials. The aluminum-doped cobalt carbonate material has a core-shell structure, wherein both the outer shell and the inner core of the core-shell structure are aluminum-doped cobalt carbonate. The overall crystallite size of the aluminum-doped cobalt carbonate material is greater than 15 nm, while the crystallite size of the inner core is less than 20 nm. Furthermore, the ratio of the overall crystallite size of the aluminum-doped cobalt carbonate material to the crystallite size of the inner core is greater than 1.05.

[0006] Existing methods for preparing aluminum-doped lithium cobalt oxide precursors have certain drawbacks. Specifically, excessively high aluminum doping levels can lead to localized aluminum segregation during the preparation process, resulting in cracking of aluminum-doped cobalt oxide particles and the formation of small particles. This deteriorates the performance of the resulting aluminum-doped lithium cobalt oxide precursor. Therefore, the development and design of a novel aluminum-doped lithium cobalt oxide precursor, its preparation method, and its application are crucial. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention aims to provide an aluminum-doped lithium cobalt oxide precursor and a preparation method and application thereof. In the present invention, in the nucleation stage, cobalt chloride is used to prepare the inner core as a seed crystal, ensuring that the inner core prepared in the early stage has high uniformity and relatively few inclusions of impurity elements; in the growth stage, cobalt sulfate is used as a Co source, which effectively prevents the explosion of the core and the appearance of multiple heads; in the final stage, a solution containing cobalt chloride and cobalt sulfate is used as a Co source, which prevents the increase of S inclusions and further prevents the problem of explosion of the core; therefore, the preparation method can avoid the problem of particle cracking and explosion of small particles in aluminum-doped cobalt tetroxide under high aluminum doping content, and the lithium cobalt oxide battery prepared with the obtained aluminum-doped lithium cobalt oxide precursor exhibits excellent electrochemical performance.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, the preparation method comprising:

[0010] (1) Nucleation stage: cobalt chloride solution, aluminum salt solution and precipitant solution are added to the reaction base solution to perform a first coprecipitation to obtain a solution containing the nucleus;

[0011] (2) Growth stage: adding a cobalt sulfate solution, an aluminum salt solution, and a precipitant solution to the solution containing the core obtained in step (1) to perform a second coprecipitation to obtain a solution containing a precipitate;

[0012] (3) Final stage: adding a solution containing cobalt chloride and cobalt sulfate, an aluminum salt solution, and a precipitant solution to the solution containing the precipitate obtained in step (2) to perform a third coprecipitation, and then obtaining an aluminum-doped lithium cobalt oxide precursor by heat treatment.

[0013] In the present invention, in the nucleation stage of step (1), the complexing property of chloride ions in cobalt chloride for cobalt ions is lower than that of sulfate ions for cobalt ions; therefore, cobalt chloride is used to prepare the inner core as a seed crystal, which ensures that the inner core prepared in the early stage has high uniformity (high distribution uniformity of cobalt and aluminum) and relatively few inclusions of impurity elements; in the growth stage of step (2), cobalt sulfate is used as a Co source, which effectively prevents the explosion of the core and the appearance of multiple heads; in the final stage of step (3), a solution containing cobalt chloride and cobalt sulfate is used as a Co source, which prevents the increase of S inclusions and further prevents the problem of explosion of the core; therefore, the preparation method can avoid the problem of particle cracking and explosion of small particles in aluminum-doped cobalt tetroxide under high aluminum doping content, and the lithium cobalt oxide battery prepared with the obtained aluminum-doped lithium cobalt oxide precursor exhibits excellent electrochemical performance.

[0014] Preferably, in the first coprecipitation in step (1), the concentration of cobalt ions in the added cobalt chloride solution is 100 g / L to 120 g / L, for example, it can be 100 g / L, 102 g / L, 104 g / L, 106 g / L, 108 g / L, 110 g / L, 112 g / L, 114 g / L, 116 g / L, 118 g / L or 120 g / L, but is not limited to the enumerated values, and other values ​​not enumerated within the numerical range are equally applicable.

[0015] Preferably, in the first co-precipitation of step (1), the aluminum salt in the aluminum salt solution added includes any one or a combination of at least two of aluminum sulfate, aluminum chloride or aluminum nitrate. Typical but non-limiting combinations include a combination of aluminum sulfate and aluminum chloride, a combination of aluminum chloride and aluminum nitrate, a combination of aluminum sulfate and aluminum nitrate, or a combination of aluminum sulfate, aluminum chloride and aluminum nitrate.

[0016] Preferably, in the first coprecipitation of step (1), the concentration of aluminum ions in the added aluminum salt solution is 1 g / L to 9 g / L, for example, it can be 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L or 9 g / L, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0017] Preferably, in the first co-precipitation of step (1), the precipitant in the added precipitant solution includes any one or a combination of at least two of ammonium bicarbonate, sodium carbonate, sodium bicarbonate or ammonium carbonate. Typical but non-limiting combinations include a combination of ammonium bicarbonate and sodium carbonate, a combination of sodium bicarbonate and ammonium carbonate, a combination of sodium carbonate and sodium bicarbonate, or a combination of ammonium bicarbonate, sodium carbonate and sodium bicarbonate.

[0018] Preferably, in the first co-precipitation in step (1), the concentration of the precipitant in the added precipitant solution is 210 g / L to 260 g / L, for example, it can be 210 g / L, 215 g / L, 220 g / L, 225 g / L, 230 g / L, 235 g / L, 240 g / L, 245 g / L, 250 g / L, 255 g / L or 260 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the components of the reaction base solution in step (1) include water and a precipitant solution.

[0020] Preferably, the temperature of the reaction base solution in step (1) is 35° C. to 50° C., and the pH is 7 to 9.

[0021] In the present invention, the temperature of the reaction base solution in step (1) is 35°C to 50°C, for example, it can be 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C or 50°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] In the present invention, the pH of the reaction base solution in step (1) is 7 to 9, for example, it can be 7.0, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6, 8.8 or 9.0, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, in the first coprecipitation in step (1), the temperature of the reaction solution is controlled to be 35°C to 50°C, for example, it can be 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0024] Preferably, in the first coprecipitation of step (1), the flow ratio of the cobalt chloride solution to the precipitant solution is controlled to be 1:(2-2.5), for example, it can be 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4 or 1:2.5, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0025] Preferably, in the first co-precipitation of step (1), the mass ratio of cobalt element to aluminum element in the reaction solution is controlled to be 72:(1-2), for example, it can be 72:1, 72:1.2, 72:1.4, 72:1.6, 72:1.8 or 72:2, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0026] Preferably, in the first coprecipitation of step (1), the pH of the reaction solution is controlled to be 7 to 9, for example, it can be 7.0, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6, 8.8 or 9.0, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0027] Preferably, the first co-precipitation in step (1) is accompanied by stirring at a speed of 200 r / min to 300 r / min, for example, it can be 200 r / min, 210 r / min, 220 r / min, 230 r / min, 240 r / min, 250 r / min, 260 r / min, 270 r / min, 280 r / min, 290 r / min or 300 r / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, at the end of the first coprecipitation in step (1), the D50 particle size of the core in the reaction solution is 5 μm to 9 μm, for example, it can be 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm or 9 μm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0029] Preferably, the temperature during the second coprecipitation in step (2) is lower than the temperature during the first coprecipitation in step (1).

[0030] Preferably, the addition flow rate of the precipitant solution during the second coprecipitation in step (2) is higher than the addition flow rate of the precipitant solution during the first coprecipitation in step (1).

[0031] In the present invention, during the growth stage of step (2), by lowering the coprecipitation temperature and increasing the flow rate of the precipitant solution added during the second coprecipitation, and using cobalt sulfate as the Co source, the explosion of nuclei and the appearance of multiple heads are effectively prevented.

[0032] Preferably, in the second coprecipitation in step (2), the concentration of cobalt ions in the added cobalt chloride solution is 100 g / L to 120 g / L, for example, it can be 100 g / L, 102 g / L, 104 g / L, 106 g / L, 108 g / L, 110 g / L, 112 g / L, 114 g / L, 116 g / L, 118 g / L or 120 g / L, but is not limited to the enumerated values, and other values ​​not enumerated within the numerical range are equally applicable.

[0033] Preferably, in the second co-precipitation of step (2), the aluminum salt in the added aluminum salt solution includes any one or a combination of at least two of aluminum sulfate, aluminum chloride or aluminum nitrate. Typical but non-limiting combinations include a combination of aluminum sulfate and aluminum chloride, a combination of aluminum chloride and aluminum nitrate, a combination of aluminum sulfate and aluminum nitrate, or a combination of aluminum sulfate, aluminum chloride and aluminum nitrate.

[0034] Preferably, in the second coprecipitation in step (2), the concentration of aluminum ions in the added aluminum salt solution is 1 g / L to 9 g / L, for example, it can be 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L or 9 g / L, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0035] Preferably, in the second co-precipitation of step (2), the precipitant in the added precipitant solution includes any one or a combination of at least two of ammonium bicarbonate, sodium carbonate, sodium bicarbonate or ammonium carbonate. Typical but non-limiting combinations include a combination of ammonium bicarbonate and sodium carbonate, a combination of sodium bicarbonate and ammonium carbonate, a combination of sodium carbonate and sodium bicarbonate, a combination of ammonium bicarbonate and sodium bicarbonate, or a combination of ammonium bicarbonate, sodium carbonate and sodium bicarbonate.

[0036] Preferably, in the second co-precipitation in step (2), the concentration of the precipitant in the added precipitant solution is 210 g / L to 260 g / L, for example, it can be 210 g / L, 215 g / L, 220 g / L, 225 g / L, 230 g / L, 235 g / L, 240 g / L, 245 g / L, 250 g / L, 255 g / L or 260 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0037] Preferably, in the second coprecipitation in step (2), the temperature of the reaction solution is controlled to be 35°C to 45°C, for example, it can be 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C or 45°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0038] Preferably, in the second co-precipitation of step (2), the flow ratio of the cobalt sulfate solution to the precipitant solution is controlled to be 1:(2.5-3), for example, it can be 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3.0, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0039] Preferably, in the second co-precipitation of step (2), the mass ratio of cobalt element to aluminum element in the reaction solution is controlled to be 72:(1-2), for example, it can be 72:1, 72:1.2, 72:1.4, 72:1.6, 72:1.8 or 72:2, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0040] Preferably, in the second co-precipitation of step (2), the pH of the reaction solution is controlled to be 7.5 to 9.5, for example, it can be 7.5, 7.7, 7.9, 8.1, 8.3, 8.5, 8.7, 8.9, 9.1, 9.3 or 9.5, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0041] Preferably, the second co-precipitation in step (2) is accompanied by stirring at a speed of 200 r / min to 300 r / min, for example, it can be 200 r / min, 210 r / min, 220 r / min, 230 r / min, 240 r / min, 250 r / min, 260 r / min, 270 r / min, 280 r / min, 290 r / min or 300 r / min, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0042] Preferably, at the end of the second co-precipitation in step (2), the D50 particle size of the precipitate in the reaction solution is 12 μm to 16 μm, for example, it can be 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm or 16 μm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0043] Preferably, the temperature during the third coprecipitation in step (3) is higher than the temperature during the second coprecipitation in step (2).

[0044] In the present invention, in the final stage of step (3), the temperature is increased during the third coprecipitation relative to the second coprecipitation, thereby increasing the degree of crystallization on the surface of the aluminum-doped lithium cobalt oxide precursor, allowing aluminum to exist in a more stable AlOOH form. At the same time, a solution containing cobalt chloride and cobalt sulfate is switched as the Co source, thereby preventing an increase in S inclusions during the third coprecipitation in the final stage and also preventing nuclear explosion during the third coprecipitation.

[0045] Preferably, in the third coprecipitation of step (3), the concentration of cobalt ions in the solution containing cobalt chloride and cobalt sulfate added is 100 g / L to 120 g / L, for example, it can be 100 g / L, 102 g / L, 104 g / L, 106 g / L, 108 g / L, 110 g / L, 112 g / L, 114 g / L, 116 g / L, 118 g / L or 120 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are equally applicable.

[0046] Preferably, in the third coprecipitation of step (3), the aluminum salt in the aluminum salt solution added includes any one or a combination of at least two of aluminum sulfate, aluminum chloride or aluminum nitrate. Typical but non-limiting combinations include a combination of aluminum sulfate and aluminum chloride, a combination of aluminum chloride and aluminum nitrate, a combination of aluminum sulfate and aluminum nitrate, or a combination of aluminum sulfate, aluminum chloride and aluminum nitrate.

[0047] Preferably, in the third coprecipitation of step (3), the concentration of aluminum ions in the added aluminum salt solution is 1 g / L to 9 g / L, for example, it can be 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L or 9 g / L, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0048] Preferably, in the third co-precipitation of step (3), the precipitant in the added precipitant solution includes any one or a combination of at least two of ammonium bicarbonate, sodium carbonate, sodium bicarbonate or ammonium carbonate. Typical but non-limiting combinations include a combination of ammonium bicarbonate and sodium carbonate, a combination of sodium bicarbonate and ammonium carbonate, a combination of sodium carbonate and sodium bicarbonate, a combination of ammonium bicarbonate and sodium bicarbonate, or a combination of ammonium bicarbonate, sodium carbonate and sodium bicarbonate.

[0049] Preferably, in the third co-precipitation of step (3), the concentration of the precipitant in the added precipitant solution is 210 g / L to 260 g / L, for example, it can be 210 g / L, 215 g / L, 220 g / L, 225 g / L, 230 g / L, 235 g / L, 240 g / L, 245 g / L, 250 g / L, 255 g / L or 260 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] Preferably, in the third coprecipitation in step (3), the temperature of the reaction solution is controlled to be 50°C to 70°C, for example, it can be 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0051] Preferably, in the third coprecipitation of step (3), the flow ratio of the solution containing cobalt chloride and cobalt sulfate to the precipitant solution is controlled to be 1:(1.5-2), for example, it can be 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.0, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0052] Preferably, in the third coprecipitation of step (3), the mass ratio of cobalt element to aluminum element in the reaction solution is controlled to be 72:(1-2), for example, it can be 72:1, 72:1.2, 72:1.4, 72:1.6, 72:1.8 or 72:2, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0053] Preferably, in the third coprecipitation of step (3), the pH of the reaction solution is controlled to be 7 to 9, for example, 7.0, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6, 8.8 or 9.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] Preferably, the third coprecipitation in step (3) is accompanied by stirring at a speed of 200 r / min to 300 r / min, for example, it can be 200 r / min, 210 r / min, 220 r / min, 230 r / min, 240 r / min, 250 r / min, 260 r / min, 270 r / min, 280 r / min, 290 r / min or 300 r / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] Preferably, at the end of the third coprecipitation in step (3), the D50 particle size of the precipitate in the reaction solution is 20 μm to 22 μm, for example, it can be 20.0 μm, 20.2 μm, 20.4 μm, 20.6 μm, 20.8 μm, 21.0 μm, 21.2 μm, 21.4 μm, 21.6 μm, 21.8 μm or 22.0 μm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0056] Preferably, step (3) further includes washing and drying performed sequentially between the third coprecipitation and the heat treatment.

[0057] Preferably, the washing is carried out with water at 50°C to 80°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0058] Preferably, the drying temperature is 50-120°C, for example, it can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0059] Preferably, the heat treatment includes heating and holding in sequence, the holding temperature is the end temperature of heating, the holding temperature is 450° C. to 600° C., and the holding time is 30 min to 120 min.

[0060] In the present invention, the insulation temperature is 450℃~600℃, for example, it can be 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃ or 600℃, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0061] In the present invention, the insulation time is 30 min to 120 min, for example, it can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, 105 min, 110 min, 115 min or 120 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0062] Preferably, the heating rate is 5°C / min to 20°C / min, for example, it can be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, 15°C / min, 16°C / min, 17°C / min, 18°C / min, 19°C / min or 20°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] Preferably, the heat treatment is carried out in an ambient atmosphere with an oxygen concentration of 15 to 25%, for example, it can be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24% or 25%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0064] As a preferred technical solution of the preparation method of the present invention, the preparation method comprises:

[0065] (1) Nucleation stage: a cobalt chloride solution with a cobalt ion concentration of 100 g / L to 120 g / L, an aluminum salt solution with an aluminum ion concentration of 1 g / L to 9 g / L, and a precipitant solution with a precipitant concentration of 210 g / L to 260 g / L are added to a reaction base solution with a temperature of 35°C to 50°C and a pH of 7 to 9 to form a reaction solution, the temperature of the reaction solution is controlled to be 35°C to 50°C, the flow ratio of the cobalt chloride solution to the precipitant solution is 1:(2 to 2.5), the mass ratio of the cobalt element to the aluminum element in the reaction solution is 72:(1 to 2), and the pH of the reaction solution is 7 to 9, and the reaction solution is stirred at a speed of 200 r / min to 300 r / min to perform a first coprecipitation to obtain a solution containing a core, and the core has a D50 particle size of 5 μm to 9 μm;

[0066] (2) Growth stage: adding a cobalt sulfate solution having a cobalt ion concentration of 100 g / L to 120 g / L, an aluminum salt solution having an aluminum ion concentration of 1 g / L to 9 g / L, and a precipitant solution having a precipitant concentration of 210 g / L to 260 g / L to the solution containing the core obtained in step (1) to form a reaction solution, controlling the temperature of the reaction solution to be 35 to 45° C. and lower than the temperature of the reaction solution in step (1), adding the cobalt sulfate solution and the precipitant solution at a flow ratio of 1:(2.5 to 3), the mass ratio of the cobalt element to the aluminum element in the reaction solution to be 72:(1 to 2), and the pH of the reaction solution to be 7.5 to 9.5, and stirring at a speed of 200 r / min to 300 r / min to perform a second coprecipitation to obtain a solution containing a precipitate; the D50 particle size of the precipitate is 12 μm to 16 μm;

[0067] (3) Final stage: adding a solution containing cobalt chloride and cobalt sulfate with a cobalt ion concentration of 100 g / L to 120 g / L, an aluminum salt solution with an aluminum ion concentration of 1 g / L to 9 g / L, and a precipitant solution with a precipitant concentration of 210 g / L to 260 g / L to the solution containing the precipitate obtained in step (2) to form a reaction solution, controlling the temperature of the reaction solution to be 50° C. to 70° C. and higher than the temperature of the reaction solution in step (2), the flow ratio of the solution containing cobalt chloride and cobalt sulfate to the precipitant solution to be 1:(1.5-2), and the mass ratio of the cobalt element to the aluminum element in the reaction solution to be 0.05; The ratio is 72:(1-2), and the pH of the reaction solution is 7-9, and it is stirred at a speed of 200r / min-300r / min, and filtered after a third coprecipitation to obtain a solid precipitate with a D50 particle size of 20μm-22μm; the obtained solid precipitate is washed with water at 50℃-80℃, dried at 50℃-120℃, and then heated to 450℃-600℃ at a heating rate of 5℃ / min-20℃ / min in an atmosphere with an oxygen concentration of 15-25%, and then kept warm for 30min-120min to obtain an aluminum-doped lithium cobalt oxide precursor.

[0068] In a second aspect, the present invention provides an aluminum-doped lithium cobalt oxide precursor, which is obtained by the preparation method described in the first aspect.

[0069] In a third aspect, the present invention provides an aluminum-doped lithium cobalt oxide positive electrode material, wherein the aluminum-doped lithium cobalt oxide positive electrode material is prepared from a raw material comprising the aluminum-doped lithium cobalt oxide precursor described in the second aspect.

[0070] In a fourth aspect, the present invention provides a lithium cobalt oxide battery, comprising the aluminum-doped lithium cobalt oxide positive electrode material described in the third aspect.

[0071] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0072] Compared with the prior art, the present invention has the following beneficial effects:

[0073] In the present invention, in the nucleation stage of step (1), the complexing property of chloride ions in cobalt chloride for cobalt ions is lower than that of sulfate ions for cobalt ions; therefore, cobalt chloride is used to prepare the inner core as a seed crystal, which ensures that the inner core prepared in the early stage has high uniformity (high distribution uniformity of cobalt and aluminum) and relatively few inclusions of impurity elements; in the growth stage of step (2), cobalt sulfate is used as a Co source, which effectively prevents the explosion of the core and the appearance of multiple heads; in the final stage of step (3), a solution containing cobalt chloride and cobalt sulfate is used as a Co source, which prevents the increase of S inclusions and further prevents the problem of explosion of the core; therefore, the preparation method can avoid the problem of particle cracking and explosion of small particles in aluminum-doped cobalt tetroxide under high aluminum doping content, and the lithium cobalt oxide battery prepared with the obtained aluminum-doped lithium cobalt oxide precursor exhibits excellent electrochemical performance. DETAILED DESCRIPTION

[0074] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0075] Example 1

[0076] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, the preparation method comprising:

[0077] (1) Nucleation stage: a cobalt chloride solution with a cobalt ion concentration of 110 g / L, an aluminum salt solution with an aluminum ion concentration of 5 g / L, and a precipitant solution with a precipitant concentration of 235 g / L were added to a reaction base solution with a temperature of 45° C. and a pH of 8 to form a reaction solution. The temperature of the reaction solution was controlled to be 45° C., the flow ratio of the cobalt chloride solution to the precipitant solution was 1:2.2, the mass ratio of the cobalt element to the aluminum element in the reaction solution was 72:1.5, and the pH of the reaction solution was 8. The mixture was stirred at a speed of 250 r / min to perform a first coprecipitation to obtain a solution containing a core, and the core had a D50 particle size of 7 μm.

[0078] (2) Growth stage: a cobalt sulfate solution with a cobalt ion concentration of 110 g / L, an aluminum salt solution with an aluminum ion concentration of 5 g / L, and a precipitant solution with a precipitant concentration of 235 g / L are added to the solution containing the core obtained in step (1) to form a reaction solution, the temperature of the reaction solution is controlled to be 40° C. and lower than the temperature of the reaction solution in step (1), the flow ratio of the cobalt sulfate solution to the precipitant solution is 1:2.7, the mass ratio of the cobalt element to the aluminum element in the reaction solution is 72:1.5, and the pH of the reaction solution is 8.5, and the mixture is stirred at a speed of 250 r / min to perform a second coprecipitation to obtain a solution containing a precipitate; the D50 particle size of the precipitate is 14 μm;

[0079] (3) Final stage: A solution containing cobalt chloride and cobalt sulfate with a cobalt ion concentration of 110 g / L, an aluminum salt solution with an aluminum ion concentration of 5 g / L, and a precipitant solution with a precipitant concentration of 235 g / L are added to the solution containing the precipitate obtained in step (2) to form a reaction solution, the temperature of the reaction solution is controlled to be 60°C and higher than the temperature of the reaction solution in step (2), the flow ratio of the solution containing cobalt chloride and cobalt sulfate to the precipitant solution is 1:1.6, the mass ratio of cobalt element to aluminum element in the reaction solution is 72:1.5, and the pH of the reaction solution is 7.5, and the mixture is stirred at a speed of 250 r / min, and then filtered to obtain a solid precipitate with a D50 particle size of 21 μm; the obtained solid precipitate is washed with water at 65°C, dried at 85°C, and then heated to 520°C at a heating rate of 12°C / min in an atmosphere with an oxygen concentration of 20%, and then kept warm for 75 minutes to obtain an aluminum-doped lithium cobalt oxide precursor.

[0080] Example 2

[0081] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, the preparation method comprising:

[0082] (1) Nucleation stage: a cobalt chloride solution with a cobalt ion concentration of 100 g / L, an aluminum salt solution with an aluminum ion concentration of 1 g / L, and a precipitant solution with a precipitant concentration of 210 g / L are added to a reaction base solution with a temperature of 50° C. and a pH of 7 to form a reaction solution. The temperature of the reaction solution is controlled to be 50° C., the flow ratio of the cobalt chloride solution to the precipitant solution is 1:2, the mass ratio of the cobalt element to the aluminum element in the reaction solution is 72:2, and the pH of the reaction solution is 7. The mixture is stirred at a speed of 300 r / min to perform a first coprecipitation to obtain a solution containing a core, and the core has a D50 particle size of 5 μm.

[0083] (2) Growth stage: a cobalt sulfate solution with a cobalt ion concentration of 100 g / L, an aluminum salt solution with an aluminum ion concentration of 1 g / L, and a precipitant solution with a precipitant concentration of 210 g / L are added to the solution containing the core obtained in step (1) to form a reaction solution, the temperature of the reaction solution is controlled to be 45° C. and lower than the temperature of the reaction solution in step (1), the flow ratio of the cobalt sulfate solution to the precipitant solution is 1:2.5, the mass ratio of the cobalt element to the aluminum element in the reaction solution is 72:1.5, and the pH of the reaction solution is 7.5, and the reaction solution is stirred at a speed of 300 r / min to perform a second coprecipitation to obtain a solution containing a precipitate; the D50 particle size of the precipitate is 12 μm;

[0084] (3) Final stage: adding a solution containing cobalt chloride and cobalt sulfate with a cobalt ion concentration of 100 g / L, an aluminum salt solution with an aluminum ion concentration of 1 g / L, and a precipitant solution with a precipitant concentration of 210 g / L to the solution containing the precipitate obtained in step (2) to form a reaction solution, controlling the temperature of the reaction solution to be 70°C and higher than the temperature of the reaction solution in step (2), the flow ratio of the solution containing cobalt chloride and cobalt sulfate to the precipitant solution to be 1:1.8, the mass ratio of cobalt element to aluminum element in the reaction solution to be 72:1.5, and the pH of the reaction solution to be 8.5, and stirring at a speed of 300 r / min, performing a third coprecipitation and then filtering to obtain a solid precipitate with a D50 particle size of 20 μm; washing the obtained solid precipitate with 80°C water, drying it at 120°C, and then heating it to 600°C at a heating rate of 20°C / min in an atmosphere with an oxygen concentration of 15%, and then keeping it warm for 30 minutes to obtain an aluminum-doped lithium cobalt oxide precursor.

[0085] Example 3

[0086] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, the preparation method comprising:

[0087] (1) Nucleation stage: a cobalt chloride solution with a cobalt ion concentration of 120 g / L, an aluminum salt solution with an aluminum ion concentration of 9 g / L, and a precipitant solution with a precipitant concentration of 260 g / L were added to a reaction base solution with a temperature of 38° C. and a pH of 9 to form a reaction solution. The temperature of the reaction solution was controlled to be 38° C., the flow ratio of the cobalt chloride solution to the precipitant solution was 1:2.5, the mass ratio of the cobalt element to the aluminum element in the reaction solution was 72:1, and the pH of the reaction solution was 9. The mixture was stirred at a speed of 200 r / min to perform a first coprecipitation to obtain a solution containing a core, and the core had a D50 particle size of 9 μm.

[0088] (2) Growth stage: a cobalt sulfate solution with a cobalt ion concentration of 120 g / L, an aluminum salt solution with an aluminum ion concentration of 9 g / L, and a precipitant solution with a precipitant concentration of 260 g / L are added to the solution containing the core obtained in step (1) to form a reaction solution, the temperature of the reaction solution is controlled to be 35° C. and lower than the temperature of the reaction solution in step (1), the flow ratio of the cobalt sulfate solution to the precipitant solution is 1:3, the mass ratio of the cobalt element to the aluminum element in the reaction solution is 72:1.5, and the pH of the reaction solution is 9.5, and the mixture is stirred at a speed of 200 r / min to perform a second coprecipitation to obtain a solution containing a precipitate; the D50 particle size of the precipitate is 16 μm;

[0089] (3) Final stage: A solution containing cobalt chloride and cobalt sulfate with a cobalt ion concentration of 120 g / L, an aluminum salt solution with an aluminum ion concentration of 9 g / L, and a precipitant solution with a precipitant concentration of 260 g / L are added to the solution containing the precipitate obtained in step (2) to form a reaction solution, the temperature of the reaction solution is controlled to be 50°C and higher than the temperature of the reaction solution in step (2), the flow ratio of the solution containing cobalt chloride and cobalt sulfate to the precipitant solution is 1:2, the mass ratio of cobalt element to aluminum element in the reaction solution is 72:1.5, and the pH of the reaction solution is 9, and the mixture is stirred at a speed of 200 r / min, and then filtered to obtain a solid precipitate with a D50 particle size of 22 μm; the obtained solid precipitate is washed with 50°C water, dried at 50°C, and then heated to 450°C at a heating rate of 5°C / min in an atmosphere with an oxygen concentration of 25%, and then kept warm for 120 minutes to obtain an aluminum-doped lithium cobalt oxide precursor.

[0090] Example 4

[0091] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as that of Example 1 except that the mass ratio of cobalt element to aluminum element in the reaction solution in steps (1) to (3) is controlled to be 72:1.

[0092] Example 5

[0093] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as that of Example 1 except that the mass ratio of cobalt element to aluminum element in the reaction solution in steps (1) to (3) is controlled to be 72:2.

[0094] Example 6

[0095] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as that of Example 1 except that the temperature of the reaction solution is controlled to be 25° C. in step (1).

[0096] Example 7

[0097] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as that of Example 1 except that the temperature of the reaction solution is controlled to be 60° C. in step (1).

[0098] Example 8

[0099] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as that of Example 1 except that the flow ratio of the cobalt sulfate solution to the precipitant solution added in step (2) is 1:2.2, that is, the pH of the reaction solution is 8.

[0100] Example 9

[0101] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as that of Example 1 except that the flow ratio of the cobalt sulfate solution to the precipitant solution added in step (2) is 1:1.5, that is, the pH of the reaction solution is 7.4.

[0102] Example 10

[0103] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as that of Example 1 except that the temperature of the reaction solution in step (3) is controlled to be 40° C., which is equal to the temperature of the reaction solution in step (2).

[0104] Example 11

[0105] This embodiment provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as that of Example 1 except that the temperature of the reaction solution in step (3) is controlled to 35° C., which is lower than the temperature of the reaction solution in step (2).

[0106] Comparative Example 1

[0107] This comparative example provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as Example 1 except that the cobalt sulfate solution in step (2) is replaced by a cobalt chloride solution with the same cobalt ion concentration.

[0108] Comparative Example 2

[0109] This comparative example provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as Example 1 except that the solution containing cobalt chloride and cobalt sulfate in step (3) is replaced by a cobalt chloride solution with the same cobalt ion concentration.

[0110] Comparative Example 3

[0111] This comparative example provides a method for preparing an aluminum-doped lithium cobalt oxide precursor, which is the same as Example 1 except that the cobalt sulfate solution in step (2) is replaced by a cobalt chloride solution with the same cobalt ion concentration, and the solution containing cobalt chloride and cobalt sulfate in step (3) is replaced by a cobalt chloride solution with the same cobalt ion concentration.

[0112] The aluminum-doped lithium cobalt oxide precursor provided in the above examples and comparative examples was mixed with lithium hydroxide and then heat-treated at 600° C. for 250 min to obtain a lithium cobalt oxide positive electrode material.

[0113] The obtained lithium cobalt oxide positive electrode material is used to prepare a lithium ion battery: the obtained lithium cobalt oxide positive electrode material, conductive carbon black SP (TIMCAL) and polyvinylidene fluoride PVDF (HSV900) are mixed in a mass ratio of 90:5:5, N-methylpyrrolidone is used as the solvent, and the mixture is stirred into a slurry. The obtained slurry is evenly coated on an aluminum foil with a scraper with a coating gap of 100 μm; after coating, it is first blown dried, then rolled and cut into circular electrode sheets, and then vacuum dried at 120°C and the weight of the electrode sheets is weighed to obtain a button half-cell positive electrode sheet; a metal lithium sheet is selected as the negative electrode, a PP microporous membrane is selected as the diaphragm, and a lithium battery basic electrolyte is selected as the electrolyte. The positive electrode sheet, the metal lithium sheet, the diaphragm and the electrolyte are assembled to obtain a button battery.

[0114] The obtained button battery was charged and discharged at 0.1C / 0.1C, and the charge and discharge test was carried out in the voltage window of 2.8~4.3V. The capacity retention rate of the button battery after 100 cycles at 0.1C is shown in Table 1; the button battery was charged and discharged at 0.1C / 1C, and the charge and discharge test was carried out in the voltage window of 2.8~4.3V. The 1C rate of the button battery is shown in Table 1.

[0115] Table 1

[0116]

[0117]

[0118] From Table 1, we can get:

[0119] (1) After the aluminum-doped lithium cobalt oxide precursor is prepared by the preparation method of the aluminum-doped lithium cobalt oxide precursor provided in Examples 1 to 5, the battery prepared with the aluminum-doped lithium cobalt oxide precursor exhibits high rate performance and strong cycle stability;

[0120] (2) By comparing Example 1 with Examples 6 to 9, it can be seen that in the preparation method of the aluminum-doped lithium cobalt oxide precursor provided in the present invention, in the growth stage of step (2), by lowering the temperature during coprecipitation and increasing the addition flow rate of the precipitant solution during the second coprecipitation, and using cobalt sulfate as the Co source, the explosion of nuclei and the appearance of multiple heads are effectively prevented; therefore, in the growth stage of step (2), by lowering the temperature during coprecipitation and increasing the addition flow rate of the precipitant solution during the second coprecipitation, the aluminum-doped lithium cobalt oxide precursor prepared by the preparation method and the battery prepared with the aluminum-doped lithium cobalt oxide precursor exhibit better electrochemical performance;

[0121] (3) By comparing Example 1 with Examples 10 and 11, it can be seen that in the present invention, in the final stage of step (3), the temperature is increased during the third coprecipitation relative to the second coprecipitation, thereby increasing the degree of crystallization on the surface of the aluminum-doped lithium cobalt oxide precursor, so that aluminum exists in a more stable AlOOH form, and at the same time, switching to a solution containing cobalt chloride and cobalt sulfate as a Co source prevents the increase of S inclusions during the third coprecipitation in the final stage, and also prevents the nuclear explosion during the third coprecipitation; therefore, after the temperature is increased during the third coprecipitation relative to the second coprecipitation, the aluminum-doped lithium cobalt oxide precursor prepared by the preparation method and the battery prepared using the aluminum-doped lithium cobalt oxide precursor exhibit better electrochemical performance;

[0122] (4) By comparing Example 1 with Comparative Examples 1 to 3, it can be seen that in the present invention, in the nucleation stage of step (1), the complexing property of chloride ions in cobalt chloride to cobalt ions is lower than that of sulfate ions to cobalt ions; therefore, cobalt chloride is used to prepare the inner core as a seed crystal, which ensures that the inner core prepared in the early stage has high uniformity (high distribution uniformity of cobalt and aluminum) and relatively few inclusions of impurity elements; in the present invention, in the growth stage of step (2), cobalt sulfate is used as a Co source, which effectively prevents the explosion of nuclei and the appearance of multiple heads; in the final stage of step (3), a solution containing cobalt chloride and cobalt sulfate is used as a Co source, which prevents the increase of S inclusions and further prevents the problem of explosion of nuclei; therefore, the preparation method can avoid the problem of particle cracking and explosion of small particles in aluminum-doped cobalt tetroxide under high aluminum doping conditions, and the lithium cobalt oxide battery prepared with the obtained aluminum-doped lithium cobalt oxide precursor exhibits excellent electrochemical properties.

[0123] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an aluminum-doped lithium cobalt oxide precursor, characterized in that: The preparation method comprises: (1) Nucleation stage: cobalt chloride solution, aluminum salt solution and precipitant solution are added to the reaction base solution to perform a first coprecipitation to obtain a solution containing the nucleus; (2) Growth stage: adding a cobalt sulfate solution, an aluminum salt solution, and a precipitant solution to the solution containing the core obtained in step (1) to perform a second coprecipitation to obtain a solution containing a precipitate; (3) Final stage: adding a solution containing cobalt chloride and cobalt sulfate, an aluminum salt solution, and a precipitant solution to the solution containing the precipitate obtained in step (2) to perform a third coprecipitation, and then obtaining an aluminum-doped lithium cobalt oxide precursor by heat treatment.

2. The preparation method according to claim 1, characterized in that In step (1) of the first coprecipitation, the temperature of the reaction solution is controlled to be 35° C. to 50° C.; Preferably, in the first coprecipitation in step (1), the flow ratio of the cobalt chloride solution to the precipitant solution is controlled to be 1:(2-2.5); Preferably, in the first coprecipitation of step (1), the mass ratio of cobalt element to aluminum element in the reaction solution is controlled to be 72:(1-2); Preferably, in the first co-precipitation in step (1), the pH of the reaction solution is controlled to be 7 to 9; Preferably, at the end of the first coprecipitation in step (1), the D50 particle size of the core in the reaction solution is 5 μm to 9 μm.

3. The preparation method according to claim 1, characterized in that The temperature during the second coprecipitation in step (2) is lower than the temperature during the first coprecipitation in step (1); Preferably, the addition flow rate of the precipitant solution during the second coprecipitation in step (2) is higher than the addition flow rate of the precipitant solution during the first coprecipitation in step (1).

4. The preparation method according to claim 3, characterized in that In step (2) of the second coprecipitation, the temperature of the reaction solution is controlled to be 35° C. to 45° C.; Preferably, in the second co-precipitation of step (2), the flow ratio of the cobalt sulfate solution to the precipitant solution is controlled to be 1:(2.5-3); Preferably, in the second co-precipitation of step (2), the mass ratio of cobalt element to aluminum element in the reaction solution is controlled to be 72:(1-2); Preferably, in the second co-precipitation of step (2), the pH of the reaction solution is controlled to be 7.5 to 9.5; Preferably, at the end of the second co-precipitation in step (2), the D50 particle size of the precipitate in the reaction solution is 12 μm to 16 μm.

5. The preparation method according to any one of claims 1 to 4, characterized in that The temperature during the third coprecipitation in step (3) is higher than the temperature during the second coprecipitation in step (2).

6. The preparation method according to claim 5, characterized in that In the third coprecipitation of step (3), the temperature of the reaction solution is controlled to be 50° C. to 70° C.; Preferably, in the third coprecipitation of step (3), the flow ratio of the solution containing cobalt chloride and cobalt sulfate to the precipitant solution is controlled to be 1:(1.5-2); Preferably, in the third coprecipitation of step (3), the mass ratio of cobalt element to aluminum element in the reaction solution is controlled to be 72:(1-2); Preferably, in the third coprecipitation of step (3), the pH of the reaction solution is controlled to be 7 to 9; Preferably, at the end of the third coprecipitation in step (3), the D50 particle size of the precipitate in the reaction solution is 20 μm to 22 μm; Preferably, the heat treatment includes heating and holding in sequence, the holding temperature is the end temperature of the heating, the holding temperature is 450° C. to 600° C., and the holding time is 30 min to 120 min; Preferably, the heating rate is 5°C / min to 20°C / min; Preferably, the heat treatment is performed in an atmosphere with an oxygen concentration of 15-25%.

7. The preparation method according to claim 1, characterized in that The preparation method comprises: (1) Nucleation stage: a cobalt chloride solution with a cobalt ion concentration of 100 g / L to 120 g / L, an aluminum salt solution with an aluminum ion concentration of 1 g / L to 9 g / L, and a precipitant solution with a precipitant concentration of 210 g / L to 260 g / L are added to a reaction base solution with a temperature of 35°C to 50°C and a pH of 7 to 9 to form a reaction solution, the temperature of the reaction solution is controlled to be 35°C to 50°C, the flow ratio of the cobalt chloride solution to the precipitant solution is 1:(2 to 2.5), the mass ratio of the cobalt element to the aluminum element in the reaction solution is 72:(1 to 2), and the pH of the reaction solution is 7 to 9, and the reaction solution is stirred at a speed of 200 r / min to 300 r / min to perform a first coprecipitation to obtain a solution containing a core, and the core has a D50 particle size of 5 μm to 9 μm; (2) Growth stage: adding a cobalt sulfate solution having a cobalt ion concentration of 100 g / L to 120 g / L, an aluminum salt solution having an aluminum ion concentration of 1 g / L to 9 g / L, and a precipitant solution having a precipitant concentration of 210 g / L to 260 g / L to the solution containing the core obtained in step (1) to form a reaction solution, controlling the temperature of the reaction solution to be 35 to 45° C. and lower than the temperature of the reaction solution in step (1), adding the cobalt sulfate solution and the precipitant solution at a flow ratio of 1:(2.5 to 3), the mass ratio of the cobalt element to the aluminum element in the reaction solution to be 72:(1 to 2), and the pH of the reaction solution to be 7.5 to 9.5, and stirring at a speed of 200 r / min to 300 r / min to perform a second coprecipitation to obtain a solution containing a precipitate; the D50 particle size of the precipitate is 12 μm to 16 μm; (3) Final stage: adding a solution containing cobalt chloride and cobalt sulfate with a cobalt ion concentration of 100 g / L to 120 g / L, an aluminum salt solution with an aluminum ion concentration of 1 g / L to 9 g / L, and a precipitant solution with a precipitant concentration of 210 g / L to 260 g / L to the solution containing the precipitate obtained in step (2) to form a reaction solution, controlling the temperature of the reaction solution to be 50° C. to 70° C. and higher than the temperature of the reaction solution in step (2), the flow ratio of the solution containing cobalt chloride and cobalt sulfate to the precipitant solution to be 1:(1.5-2), and the mass ratio of the cobalt element to the aluminum element in the reaction solution to be 1:(1.5-2). The ratio of the reaction mixture to the reaction mixture is 72:(1-2), and the pH value of the reaction solution is 7-9. The mixture is stirred at a speed of 200 r / min-300 r / min, and then filtered to obtain a solid precipitate with a D50 particle size of 20 μm-22 μm. The solid precipitate is washed with water at 50°C-80°C, dried at 50°C-120°C, and then heated to 450°C-600°C at a heating rate of 5°C / min-20°C / min in an atmosphere with an oxygen concentration of 15%-25%, and then kept warm for 30min-120min to obtain an aluminum-doped lithium cobalt oxide precursor.

8. An aluminum-doped lithium cobalt oxide precursor, characterized in that: The aluminum-doped lithium cobalt oxide precursor is obtained by the preparation method according to any one of claims 1 to 7.

9. An aluminum-doped lithium cobalt oxide positive electrode material, characterized in that: The aluminum-doped lithium cobalt oxide positive electrode material is prepared from raw materials comprising the aluminum-doped lithium cobalt oxide precursor according to claim 8.

10. A lithium cobalt oxide battery, characterized in that: The lithium cobalt oxide battery comprises the aluminum-doped lithium cobalt oxide positive electrode material according to claim 9.

Images