Method for reducing specific surface area of aluminum-doped ternary precursor

Abstract

The invention relates to a method for reducing the specific surface area of an aluminum-doped ternary precursor, which comprises the following steps: at the stirring speed of 380r / min-400r / min, introducing a ternary mixed salt solution, an aluminum salt solution, a precipitator solution and a complexing agent solution into a base solution in parallel, and carrying out first coprecipitation reaction until the particle size D50 reaches 1.5 mu m-1. 7mu m; adjusting the flow of the precipitant solution, maintaining the high pH value in the system, and carrying out a second coprecipitation reaction to obtain an aluminum-doped ternary precursor with the particle size D50 of 3.5-4.1 [mu] m; during the first coprecipitation reaction, the concentration of the complexing agent in the system is 0.5 mol / L to 0.6 mol / L. According to the method provided by the invention, through the cooperation of the stirring speed and the concentration of the complexing agent, a compact crystal nucleus can be obtained in the first coprecipitation reaction, and then the aluminum-doped ternary precursor with a relatively small specific surface area can be obtained through the second coprecipitation reaction.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical technology and relates to a method for preparing an aluminum-doped ternary precursor, and more particularly to a method for reducing the specific surface area of ​​the aluminum-doped ternary precursor. Background Technology

[0002] As the mainstream energy storage device, the performance improvement of lithium-ion batteries depends on the optimization of cathode materials. Ternary materials such as NCM or NCA are widely studied due to their high specific capacity and low cost, but ternary precursors prepared using traditional processes typically have a high specific surface area. Furthermore, the doping of aluminum can alter the crystal growth habit of ternary precursors, forming more surface defect sites, which can further increase the specific surface area of ​​the ternary precursors.

[0003] A high specific surface area leads to an increase in active sites on the surface of ternary precursors, which can easily cause excessive oxidation during high-temperature sintering, generating rock salt phase impurities and reducing the electrochemical activity and cycle stability of the cathode material. Furthermore, a high specific surface area also increases the side reaction interface between the cathode material and the electrolyte, accelerating electrolyte decomposition and leading to increased internal resistance and capacity decay in lithium-ion batteries. Existing technologies often reduce the specific surface area of ​​ternary precursors by increasing the calcination temperature or extending the calcination time, but this can cause excessive grain growth, affecting ion diffusion channels. Some existing technologies use dispersants to reduce the specific surface area, but complexing agents generate a large amount of gas during high-temperature decomposition, which can easily form microporous defects inside the ternary precursor, increasing the impedance of the lithium-ion battery.

[0004] Therefore, achieving precise control of the specific surface area of ​​aluminum-doped ternary precursors has become a key breakthrough in improving the overall performance of cathode materials. Reducing the specific surface area of ​​aluminum-doped ternary precursors not only decreases the contact interface between the corresponding cathode material and the electrolyte, suppressing the dissolution of transition metal ions and electrolyte decomposition reactions during cycling, but also optimizes the sintering kinetics of the cathode material, promoting the sufficiency and uniformity of the lithiation reaction, thereby significantly improving the cycle life, thermal stability, and rate performance of the cathode material. This invention is based on this need and proposes a method for reducing the specific surface area of ​​aluminum-doped ternary precursors, aiming to solve the technical bottlenecks existing in the prior art. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for reducing the specific surface area of ​​aluminum-doped ternary precursors, which can yield aluminum-doped ternary precursors with smaller specific surface areas when aluminum is doped.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] This invention provides a method for reducing the specific surface area of ​​an aluminum-doped ternary precursor, the method comprising:

[0008] At a stirring speed of 380 r / min to 400 r / min, a ternary mixed salt solution, an aluminum salt solution, a precipitant solution, and a complexing agent solution are introduced concurrently into the bottom liquid to carry out the first coprecipitation reaction until the particle size D50 reaches 1.5 μm to 1.7 μm;

[0009] The flow rate of the precipitant solution was adjusted to maintain the pH value in the system for the second coprecipitation reaction, resulting in an aluminum-doped ternary precursor with a particle size D50 of 3.5 μm to 4.1 μm.

[0010] During the first coprecipitation reaction, the concentration of the complexing agent in the system is 0.5 mol / L to 0.6 mol / L.

[0011] The method provided by this invention, through the synergy of stirring speed and complexing agent concentration, can obtain dense crystal nuclei in the first coprecipitation reaction, and then obtain aluminum-doped ternary precursors with small specific surface area through the second coprecipitation reaction.

[0012] Preferably, the stirring speed of the second coprecipitation reaction is 300 r / min to 380 r / min.

[0013] Preferably, the pH value of the first coprecipitation reaction is higher than the pH value of the second coprecipitation reaction.

[0014] Preferably, the pH value of the first coprecipitation reaction is 11.7 to 12.0.

[0015] Preferably, the pH value of the second coprecipitation reaction is 11.6 to 11.8.

[0016] Preferably, during the second coprecipitation reaction, the concentration of the complexing agent in the system is 0.6 mol / L to 0.7 mol / L.

[0017] Preferably, the complexing agent in the complexing agent solution includes any one or a combination of at least two of ammonia, oxalic acid, citric acid, or ethylenediaminetetraacetic acid, with ammonia being the most preferred.

[0018] Preferably, the Al doping content in the aluminum-doped ternary precursor is 2000ppm to 2400ppm by mass.

[0019] Preferably, the ternary mixed salt in the ternary mixed salt solution includes nickel salt, manganese salt and cobalt salt.

[0020] Preferably, the total concentration of the ternary mixed salt in the ternary mixed salt solution is 2 mol / L to 2.5 mol / L.

[0021] Preferably, the nickel salt comprises any one or a combination of at least two of nickel sulfate, nickel chloride, or nickel nitrate.

[0022] Preferably, the manganese salt includes any one or a combination of at least two of manganese sulfate, manganese chloride, or manganese nitrate.

[0023] Preferably, the cobalt salt comprises any one or a combination of at least two of cobalt sulfate, cobalt chloride, or cobalt nitrate.

[0024] Preferably, the aluminum salt in the aluminum salt solution includes any one or a combination of at least two of aluminum sulfate, aluminum chloride, or aluminum nitrate.

[0025] Preferably, the base liquid is composed of a solvent, a complexing agent solution, and a precipitant solution.

[0026] Preferably, the pH value of the base solution is 11.7 to 12.0.

[0027] Preferably, the concentration of the complexing agent in the base solution is 0.5 mol / L to 0.6 mol / L.

[0028] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The method provided by this invention, through the synergy of stirring speed and complexing agent concentration, can obtain dense crystal nuclei in the first coprecipitation reaction, and then obtain aluminum-doped ternary precursors with small specific surface area through the second coprecipitation reaction. Attached Figure Description

[0031] Figure 1 The image shows the SEM image of the aluminum-doped ternary precursor obtained in Example 1. Detailed Implementation

[0032] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0033] This invention provides a method for reducing the specific surface area of ​​an aluminum-doped ternary precursor, the method comprising:

[0034] At a stirring speed of 380 r / min to 400 r / min, a ternary mixed salt solution, an aluminum salt solution, a precipitant solution, and a complexing agent solution are introduced concurrently into the bottom liquid to carry out the first coprecipitation reaction until the particle size D50 reaches 1.5 μm to 1.7 μm;

[0035] The flow rate of the precipitant solution was adjusted to maintain the pH value in the system for the second coprecipitation reaction, resulting in an aluminum-doped ternary precursor with a particle size D50 of 3.5 μm to 4.1 μm.

[0036] During the first coprecipitation reaction, the concentration of the complexing agent in the system is 0.5 mol / L to 0.6 mol / L.

[0037] The method provided by this invention, through the synergy of stirring speed and complexing agent concentration, can obtain dense crystal nuclei in the first coprecipitation reaction, and then obtain aluminum-doped ternary precursors with small specific surface area through the second coprecipitation reaction.

[0038] The density of the crystal nuclei is key to reducing the specific surface area of ​​the aluminum-doped ternary precursor. In this invention, a complexing agent concentration of 0.5 mol / L to 0.6 mol / L is used in the first coprecipitation reaction to ensure that the metal ions exist in a complexed state. This prevents the formation of excessively small crystal nuclei due to a sudden increase in supersaturation, thus ensuring stable growth of the crystal nuclei. With the assistance of stirring speed, the relative stability of the local concentration is ensured, which in turn guarantees the stable growth of the crystal nuclei, resulting in crystal nuclei with a dense structure and low porosity. As a result, an aluminum-doped ternary precursor with a small specific surface area is obtained.

[0039] In this invention, the stirring speed of the first coprecipitation reaction is 380 r / min to 400 r / min, for example, it can be 380 r / min, 385 r / min, 390 r / min, 395 r / min or 400 r / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] In this invention, the target particle size for the first coprecipitation reaction is a particle size D50 of 1.5 μm to 1.7 μm, for example, it can be 1.5 μm, 1.6 μm or 1.7 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] In this invention, the concentration of the complexing agent in the system of the first coprecipitation reaction is 0.5 mol / L to 0.6 mol / L, for example, it can be 0.5 mol / L, 0.52 mol / L, 0.54 mol / L, 0.56 mol / L, 0.58 mol / L or 0.6 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] In this invention, the particle size D50 of the final aluminum-doped ternary precursor is 3.5 μm to 4.1 μm, for example, it can be 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, 3.9 μm, 4.0 μm or 4.1 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] In some embodiments, the stirring speed of the second coprecipitation reaction is 300 r / min to 380 r / min, for example, it can be 300 r / min, 320 r / min, 340 r / min, 360 r / min, 370 r / min or 380 r / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0044] In some embodiments, the pH value of the first coprecipitation reaction is higher than the pH value of the second coprecipitation reaction.

[0045] In some embodiments, the pH value of the first coprecipitation reaction is 11.7 to 12.0, for example, it can be 11.7, 11.75, 11.8, 11.85, 11.9 or 12.0, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] In some embodiments, the pH value of the second coprecipitation reaction is 11.6 to 11.8, for example, it can be 11.6, 11.65, 11.7, 11.75 or 11.8, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0047] In some embodiments, during the second coprecipitation reaction, the concentration of the complexing agent in the system is 0.6 mol / L to 0.7 mol / L, for example, it can be 0.6 mol / L, 0.65 mol / L or 0.7 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0048] In some embodiments, the complexing agent in the complexing agent solution includes any one or a combination of at least two of ammonia, oxalic acid, citric acid, or ethylenediaminetetraacetic acid (EDTA). Typical but non-limiting examples include combinations of ammonia and oxalic acid, combinations of oxalic acid and citric acid, combinations of oxalic acid and EDTA, combinations of oxalic acid, citric acid, and EDTA, or combinations of ammonia, oxalic acid, citric acid, and EDTA, preferably ammonia.

[0049] In some embodiments, the Al doping amount in the aluminum-doped ternary precursor is 2000ppm to 2400ppm by mass content, for example, it can be 2000ppm, 2100ppm, 2200ppm, 2300ppm or 2400ppm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0050] In some embodiments, the ternary mixed salt in the ternary mixed salt solution includes nickel salt, manganese salt, and cobalt salt.

[0051] In some embodiments, the total concentration of the ternary mixed salt in the ternary mixed salt solution is 2 mol / L to 2.5 mol / L, for example, it can be 2 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, 2.4 mol / L or 2.5 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0052] In some embodiments, the nickel salt comprises any one or a combination of at least two of nickel sulfate, nickel chloride, or nickel nitrate. Typical but non-limiting combinations include combinations of nickel sulfate and nickel chloride, nickel sulfate and nickel nitrate, nickel chloride and nickel nitrate, or nickel sulfate, nickel chloride, and nickel nitrate.

[0053] In some embodiments, the manganese salt includes any one or a combination of at least two of manganese sulfate, manganese chloride, or manganese nitrate. Typical but non-limiting combinations include combinations of manganese sulfate and manganese chloride, manganese sulfate and manganese nitrate, manganese chloride and manganese nitrate, or combinations of manganese sulfate, manganese chloride, and manganese nitrate.

[0054] In some embodiments, the cobalt salt includes any one or a combination of at least two of cobalt sulfate, cobalt chloride, or cobalt nitrate. Typical but non-limiting combinations include a combination of cobalt sulfate and cobalt chloride, a combination of cobalt sulfate and cobalt nitrate, a combination of cobalt chloride and cobalt nitrate, or a combination of cobalt sulfate, cobalt chloride, and cobalt nitrate.

[0055] In some embodiments, the aluminum salt in the 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 combinations of aluminum sulfate and aluminum chloride, aluminum sulfate and aluminum nitrate, aluminum chloride and aluminum nitrate, or combinations of aluminum sulfate, aluminum chloride, and aluminum nitrate.

[0056] In some embodiments, the base liquid consists of a solvent, a complexing agent solution, and a precipitant solution.

[0057] In some embodiments, the pH value of the substrate is 11.7 to 12.0, for example, it may be 11.7, 11.75, 11.8, 11.85, 11.9 or 12.0, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0058] In some embodiments, the concentration of the complexing agent in the substrate is 0.5 mol / L to 0.6 mol / L, for example, it can be 0.5 mol / L, 0.53 mol / L, 0.55 mol / L, 0.57 mol / L, 0.58 mol / L or 0.6 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0059] In some embodiments, the first coprecipitation reaction and the second coprecipitation reaction are carried out in a protective atmosphere. The protective atmosphere includes nitrogen and / or an inert gas, wherein the inert gas includes any one or a combination of at least two of helium, neon, or argon, and typical but non-limiting combinations include a combination of helium and neon, a combination of neon and argon, a combination of helium and argon, or a combination of helium, neon, and argon.

[0060] Example 1

[0061] This embodiment provides a method for reducing the specific surface area of ​​an aluminum-doped ternary precursor, the method comprising the following steps:

[0062] (1) Prepare the base solution, which consists of water, ammonia and sodium hydroxide solution. The pH value of the base solution is 11.9 and the concentration of ammonia is 0.55 mol / L.

[0063] Prepare a ternary mixed salt solution and an aluminum sulfate solution;

[0064] The ternary mixed salt solution comprises nickel sulfate, manganese sulfate, and cobalt sulfate, with a molar ratio of nickel, cobalt, and manganese of 8:1:1, and a total concentration of nickel sulfate, manganese sulfate, and cobalt sulfate of 2.2 mol / L.

[0065] (2) Under nitrogen atmosphere, the stirring speed is controlled at 400 r / min. A ternary mixed salt solution, aluminum sulfate solution, sodium hydroxide solution and ammonia water are introduced into the bottom liquid in parallel to carry out the first coprecipitation reaction until the particle size D50 reaches 1.6 μm.

[0066] During the first coprecipitation reaction, the pH value was 11.95 and the ammonia concentration in the system was 0.55 mol / L.

[0067] (3) Adjust the flow rate of sodium hydroxide solution to lower the pH value of the system to carry out the second coprecipitation reaction, and obtain an aluminum-doped ternary precursor with a particle size D50 of 3.95 μm (SEM image as shown). Figure 1 (As shown); the aluminum doping amount in the aluminum-doped ternary precursor is 2200 ppm.

[0068] The stirring speed for the second coprecipitation reaction was 350 r / min, the pH value was 11.7, and the ammonia concentration in the system was 0.65 mol / L.

[0069] Example 2

[0070] This embodiment provides a method for reducing the specific surface area of ​​an aluminum-doped ternary precursor, the method comprising the following steps:

[0071] (1) Prepare the base solution, which consists of water, ammonia and sodium hydroxide solution. The pH of the base solution is 12.0 and the concentration of ammonia is 0.6 mol / L.

[0072] Prepare a ternary mixed salt solution and an aluminum sulfate solution;

[0073] The ternary mixed salt solution contains nickel sulfate, manganese sulfate and cobalt sulfate, with a molar ratio of nickel, cobalt and manganese of 8:1:1, and a total concentration of nickel sulfate, manganese sulfate and cobalt sulfate of 2.5 mol / L.

[0074] (2) Under nitrogen atmosphere, the stirring speed is controlled at 400 r / min. A ternary mixed salt solution, aluminum sulfate solution, sodium hydroxide solution and ammonia water are introduced into the bottom liquid in parallel to carry out the first coprecipitation reaction until the particle size D50 reaches 1.7 μm.

[0075] During the first coprecipitation reaction, the pH value was 12.0 and the ammonia concentration in the system was 0.6 mol / L;

[0076] (3) Adjust the flow rate of sodium hydroxide solution and lower the pH value in the system to carry out the second coprecipitation reaction to obtain an aluminum-doped ternary precursor with a particle size D50 of 4.1 μm; the aluminum doping amount in the aluminum-doped ternary precursor is 2000 ppm.

[0077] The stirring speed for the second coprecipitation reaction was 380 r / min, the pH value was 11.8, and the ammonia concentration in the system was 0.7 mol / L.

[0078] Example 3

[0079] This embodiment provides a method for reducing the specific surface area of ​​an aluminum-doped ternary precursor, the method comprising the following steps:

[0080] (1) Prepare the base solution, which consists of water, ammonia and sodium hydroxide solution. The pH value of the base solution is 11.7 and the concentration of ammonia is 0.5 mol / L.

[0081] Prepare a ternary mixed salt solution and an aluminum sulfate solution;

[0082] The ternary mixed salt solution contains nickel sulfate, manganese sulfate and cobalt sulfate, with a molar ratio of nickel, cobalt and manganese of 8:1:1, and a total concentration of nickel sulfate, manganese sulfate and cobalt sulfate of 2 mol / L.

[0083] (2) Under nitrogen atmosphere, the stirring speed is controlled at 380 r / min. A ternary mixed salt solution, aluminum sulfate solution, sodium hydroxide solution and ammonia water are introduced into the bottom liquid in parallel to carry out the first coprecipitation reaction until the particle size D50 reaches 1.5 μm.

[0084] During the first coprecipitation reaction, the pH value was 11.7 and the ammonia concentration in the system was 0.5 mol / L.

[0085] (3) Adjust the flow rate of sodium hydroxide solution to lower the pH value in the system to carry out the second coprecipitation reaction and obtain an aluminum-doped ternary precursor with a particle size D50 of 3.8 μm; the aluminum doping amount in the aluminum-doped ternary precursor is 2400 ppm.

[0086] The stirring speed for the second coprecipitation reaction was 300 r / min, the pH value was 11.6, and the ammonia concentration in the system was 0.6 mol / L.

[0087] Example 4

[0088] This embodiment provides a method for reducing the specific surface area of ​​aluminum-doped ternary precursors. Except for the ammonia concentration in the system being 0.55 mol / L during the second coprecipitation reaction, all other aspects are the same as in Example 1.

[0089] Example 5

[0090] This embodiment provides a method for reducing the specific surface area of ​​aluminum-doped ternary precursors. Except for the pH value of 11.7 in the first coprecipitation reaction, the rest is the same as in Example 1.

[0091] Example 6

[0092] This embodiment provides a method for reducing the specific surface area of ​​aluminum-doped ternary precursors. Except for the pH value of the second coprecipitation reaction being 11.95, the rest of the method is the same as in Example 1.

[0093] Comparative Example 1

[0094] This comparative example provides a method for reducing the specific surface area of ​​an aluminum-doped ternary precursor. Except for the ammonia concentration in the system being 0.3 mol / L during the first and second coprecipitation reactions, the rest is the same as in Example 1.

[0095] Comparative Example 2

[0096] This comparative example provides a method for reducing the specific surface area of ​​an aluminum-doped ternary precursor. Except for the stirring speed of 280 r / min during the first coprecipitation reaction, the method is the same as in Example 1.

[0097] Performance Characterization

[0098] The specific surface area of ​​the aluminum-doped ternary precursors obtained in the above embodiments and comparative examples was measured, and the results are shown in Table 1.

[0099] Table 1

[0100] <![CDATA[BET(m 2 / g)]]> Example 1 8.5±0.5 Example 2 6.5±0.5 Example 3 9.0±0.5 Example 4 9.5±0.5 Example 5 10.5±0.5 Example 6 10.5±0.5 Comparative Example 1 12.0±0.5 Comparative Example 2 11.5±0.5

[0101] As shown in Table 1, the preferred embodiment of the present invention can achieve a specific surface area of ​​9 ± 0.5 m². 2 / g or less. A comparison of Example 4 and Example 1 shows that when the concentration of the complexing agent in the system is not appropriately reduced during the second coprecipitation reaction, the specific surface area of ​​the obtained aluminum-doped ternary precursor slightly increases to 9.5 ± 0.5 m². 2 / g. A comparison of Examples 5, 6 and Example 1 shows that when the pH values ​​of the first coprecipitate and the second coprecipitate are the same, the specific surface area of ​​the aluminum-doped ternary precursor will also increase slightly.

[0102] A comparison between Comparative Example 1 and Example 1 shows that if the ammonia concentration in the system is too low during the first coprecipitation reaction and the second coprecipitation reaction, the specific surface area of ​​the resulting aluminum-doped ternary precursor will be too high, and the purpose of reducing the specific surface area of ​​the aluminum-doped ternary precursor cannot be achieved. A comparison between Comparative Example 2 and Example 1 shows that if the stirring speed of the first coprecipitation reaction is too low, the specific surface area of ​​the resulting aluminum-doped ternary precursor will also be too high, and the purpose of reducing the specific surface area of ​​the aluminum-doped ternary precursor cannot be achieved.

[0103] In summary, the method provided by this invention, through the synergy of stirring speed and complexing agent concentration, can obtain dense crystal nuclei in the first coprecipitation reaction, and then obtain an aluminum-doped ternary precursor with a small specific surface area through the second coprecipitation reaction. The density of the crystal nuclei is the key to reducing the specific surface area of ​​the aluminum-doped ternary precursor. In the first coprecipitation reaction, this invention uses a complexing agent concentration of 0.5 mol / L to 0.6 mol / L, so that the metal ions exist in a complexed state. The system will not produce excessively small crystal nuclei due to a sudden increase in supersaturation, thus ensuring the stable growth of the crystal nuclei. With the synergy of stirring speed, the relative stability of the local concentration is ensured, which together ensures the stable growth of the crystal nuclei, resulting in crystal nuclei with a dense structure and low porosity; thus, an aluminum-doped ternary precursor with a small specific surface area is obtained.

[0104] The applicant declares that 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 conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for reducing the specific surface area of ​​an aluminum-doped ternary precursor, characterized in that, The method includes: At a stirring speed of 380 r / min to 400 r / min, a ternary mixed salt solution, an aluminum salt solution, a precipitant solution, and a complexing agent solution are introduced concurrently into the bottom liquid to carry out the first coprecipitation reaction until the particle size D50 reaches 1.5 μm to 1.7 μm; The flow rate of the precipitant solution was adjusted to maintain the pH value in the system for the second coprecipitation reaction, resulting in an aluminum-doped ternary precursor with a particle size D50 of 3.5 μm to 4.1 μm. During the first coprecipitation reaction, the concentration of the complexing agent in the system is 0.5 mol / L to 0.6 mol / L.

2. The method according to claim 1, characterized in that, The stirring speed for the second coprecipitation reaction is 300 r / min to 380 r / min.

3. The method according to claim 1, characterized in that, The pH value of the first coprecipitation reaction is higher than the pH value of the second coprecipitation reaction; And / or, the pH value of the first coprecipitation reaction is 11.7 to 12.0; And / or, the pH value of the second coprecipitation reaction is 11.6 to 11.

8.

4. The method according to claim 1, characterized in that, During the second coprecipitation reaction, the concentration of the complexing agent in the system is 0.6 mol / L to 0.7 mol / L.

5. The method according to any one of claims 1 to 4, characterized in that, The complexing agent in the complexing agent solution includes any one or a combination of at least two of ammonia, oxalic acid, citric acid, or ethylenediaminetetraacetic acid.

6. The method according to claim 1, characterized in that, The Al doping content in the aluminum-doped ternary precursor is 2000ppm to 2400ppm by mass content.

7. The method according to claim 1, characterized in that, The ternary mixed salt in the ternary mixed salt solution includes nickel salt, manganese salt and cobalt salt; And / or, in the ternary mixed salt solution, the total concentration of the ternary mixed salt is 2 mol / L to 2.5 mol / L.

8. The method according to claim 7, characterized in that, The nickel salt includes any one or a combination of at least two of nickel sulfate, nickel chloride, or nickel nitrate. And / or, the manganese salt includes any one or a combination of at least two of manganese sulfate, manganese chloride, or manganese nitrate; And / or, the cobalt salt includes any one or a combination of at least two of cobalt sulfate, cobalt chloride, or cobalt nitrate.

9. The method according to claim 1, characterized in that, The aluminum salt in the aluminum salt solution includes any one or a combination of at least two of aluminum sulfate, aluminum chloride, or aluminum nitrate.

10. The method according to claim 1, characterized in that, The base liquid consists of a solvent, a complexing agent solution, and a precipitant solution; And / or, the pH value of the substrate solution is 11.7 to 12.0; And / or, the concentration of the complexing agent in the substrate is 0.5 mol / L to 0.6 mol / L.

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