Preparation Method and Application of Aluminum-Doped Precursor for Lithium-Ion Battery Cathode Material

Abstract

The present invention discloses a preparation method and application of an aluminum-doped lithium battery cathode material precursor. An aluminum salt and one or more of nickel salts, cobalt salts, and manganese salts are dissolved in water to prepare a mixed metal solution, and another aluminum salt is selected to prepare an aluminum-alkali solution using an alkali solution as a solvent. The feeding of the mixed metal solution and the aluminum-alkali solution is controlled at a certain proportion of feeding speed, and the precursor is prepared by a co-precipitation method, which can effectively improve the sphericity of the precursor, make the particle size distribution more uniform and consistent, and is beneficial to improving the electrochemical performance of the cathode material. At the same time, the present invention reduces the formation of small balls during the preparation of the precursor by adding an additive to the bottom liquid of the kettle, which is beneficial to regulating the aspect ratio of the primary particles and improving the sphericity, and at the same time makes the particle size distribution of the precursor more uniform and consistent.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation and application of precursors for lithium-ion battery cathode materials, and particularly relates to a preparation method and application of an aluminum-doped precursor for a lithium battery cathode material. Background Art

[0002] In recent years, stimulated by the green and sustainable development policy and the enhancement of people's green environmental protection concept, with the high-speed growth of new energy vehicle sales and the stable growth of market demands such as power tools, the demand for new energy power batteries has maintained a high-speed growth. Lithium-ion batteries with high energy density and long cycle life are urgently needed in the market. The cathode material formed by sintering a ternary precursor and a lithium salt is an important part of a lithium-ion battery and is currently mainly used for the power batteries of new energy vehicles. Due to the advantages of its specific capacity and energy density, the installed capacity of ternary materials has been continuously increasing in recent years, showing broad application prospects. After high-temperature sintering, the performance of the ternary precursor is continued on the ternary cathode material. Therefore, the control process of the ternary precursor is crucial.

[0003] High-nickel ternary cathode materials have a high discharge capacity, but their cycling performance and safety will decrease. In order to seek a balance between high capacity and high stability, higher requirements are imposed on the ternary precursor. Currently, the more common high-nickel products in the market are mainly nickel cobalt manganese and nickel cobalt aluminum. The production of ternary cathode material precursors mainly uses the hydroxide co-precipitation process. However, the properties of aluminum hydroxide determine that it may not be able to co-precipitate uniformly with nickel hydroxide and cobalt hydroxide at the same time. It is very likely that aluminum hydroxide nucleates separately during the precipitation process, resulting in non-uniform particle size distribution of the precursor and relatively poor spherical morphology, which is not conducive to the sintering of the ternary cathode material and further affects the use performance of the ternary cathode material.

[0004] The patent document of CN103178262A discloses a preparation method of aluminum-doped lithium nickel cobaltate. First, soluble salt solutions of nickel and cobalt, ammonia water, and an alkali solution are simultaneously added to a reaction kettle for co-precipitation reaction. By controlling the process parameters during the preparation process, a nickel cobalt hydroxide precursor is synthesized; then the nickel cobalt hydroxide precursor obtained from the above reaction is washed to a certain condition, and a soluble aluminum salt solution is added thereto, and the process parameters during the reaction are controlled to synthesize a nickel cobalt aluminum hydroxide precursor. This patented technology discloses a method for preparing a nickel cobalt aluminum hydroxide precursor by a stepwise precipitation method. The obtained nickel cobalt aluminum hydroxide precursor has a spherical or quasi-spherical morphology. However, the stepwise precipitation process cannot achieve uniform distribution of nickel, cobalt, and aluminum elements, and the obtained nickel cobalt aluminum hydroxide precursor has non-uniform particle size distribution and relatively poor spherical morphology, which is not conducive to the sintering of the cathode material and will further affect the use performance of the cathode material.

[0005] The patent document of CN106935844A discloses a preparation method of a cathode material for a lithium-ion battery. A salt solution, an aluminum-containing alkaline solution, and a complexing agent solution are added in parallel flow into a reaction kettle with an overflow port for reaction. The precursor slurry obtained by overflow is subjected to solid-liquid separation, washing, drying, and screening to obtain a cathode material precursor. Then, it is mixed with a lithium source, sintered, crushed, and screened to obtain a uniformly aluminum-doped cathode material. This method can achieve uniform doping of aluminum elements in the precursor, and has a simple process, a smooth process flow, and a low production cost, being suitable for large-scale industrial production. However, due to the use of a single aluminum source feeding method and the absence of additives in the bottom liquid of the kettle, the particle size distribution of the prepared cathode material precursor is not uniform, forming small particle products, which is not conducive to the sintering of the cathode material and will thus affect the service performance of the cathode material.

[0006] The patent document of CN109896552A discloses a preparation method of an aluminum-doped lithium-ion cathode material precursor. A mixed solution of a cobalt solution, ammonia water, and an aluminum complexing solution is added in parallel flow into the reaction kettle from one side of the reaction kettle, and a liquid caustic solution is added into the reaction kettle in a metered manner from the other side of the reaction kettle; the solution added into the reaction kettle is stirred and mixed by a spiral stirring impeller and the pH value of the solution is controlled to be about 12.4; the uniformly mixed solution in the reaction kettle is allowed to stand, the supernatant is filtered into an aging tank, and the aged reactants are subjected to sintering and batch magnetic removal treatment to obtain a finished aluminum-doped cobalt oxide precursor. While ensuring the strength of the prepared aluminum-doped lithium-ion cathode material precursor, the distribution of aluminum elements in the prepared aluminum-doped cobalt oxide precursor is more uniform. However, due to the use of a single aluminum source feeding method and the absence of additives in the bottom liquid of the kettle, the particle size distribution of the prepared cathode material precursor is not uniform, forming small particle products, which is not conducive to the sintering of the cathode material and will thus affect the service performance of the cathode material.

[0007] Based on the problems existing in the preparation process of the aluminum-doped cathode material precursor at present, the present invention endeavors to provide a new aluminum doping method for preparing an aluminum-doped cathode material precursor, selects two aluminum sources to be fed separately in different ways, effectively solves the problems of uneven distribution of metal elements and uneven particle size distribution of the cathode material precursor in the coprecipitation process, and thus effectively improves the electrochemical performance and cyclic service performance of the cathode material prepared by subsequent sintering. There is no relevant report in this regard at present. Summary of the Invention

[0008] In order to solve the problems existing currently, such as uneven coprecipitation of aluminum element in the precursor of aluminum-doped lithium battery cathode material, relatively poor sphericity of the precursor, and uneven particle size distribution of the precursor, etc., the present invention provides a preparation method of the precursor of aluminum-doped lithium battery cathode material. In the precursor of aluminum-doped lithium battery cathode material prepared by this method, the distribution of metal elements is uniform, the sphericity of the precursor is good, and the particle size distribution of the precursor is more uniform and consistent, which is beneficial to improving the electrochemical performance of the cathode material to a certain extent. At the same time, the present invention reduces the formation of small balls in the process of precursor preparation by adding additives to the bottom solution of the kettle, which is beneficial to regulating the aspect ratio of primary particles and improving the sphericity, and at the same time makes the particle size distribution of the precursor more uniform and consistent.

[0009] The present invention adopts the following technical solutions to solve the above technical problems. A preparation method of the precursor of aluminum-doped lithium battery cathode material, the specific steps are as follows:

[0010] Step S1: Dissolve the first aluminum salt and the metal salt in pure water to prepare a mixed metal solution, where the first aluminum salt is one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum sol or sodium metaaluminate, and the metal salt is one or more of soluble nickel salt, soluble cobalt salt or soluble manganese salt;

[0011] Step S2: Dissolve the second aluminum salt in an alkali solution to prepare an aluminum-alkali solution, where the second aluminum salt is one or more of aluminum acetate, aluminum sulfate, aluminum chloride, aluminum nitrate or sodium metaaluminate;

[0012] Step S3: Add pure water, an alkali solution, a complexing agent and an additive into a reaction kettle to prepare a mixed solution as the bottom solution of the kettle, where the complexing agent is one or more of ammonia water, urea, citric acid or sodium citrate, and the additive is one or more of sodium sulfate, potassium sulfate or cesium sulfate;

[0013] Step S4: Flow the mixed metal solution obtained in Step S1, the aluminum-alkali solution obtained in Step S2, the alkali solution and the complexing agent into the reaction kettle in parallel, control the pH value of the reaction system to be 10.0~14.0, the rotation speed to be 200~1000 rpm, and carry out coprecipitation reaction at 30~90 °C to obtain a precursor slurry. After washing, dehydrating, drying and sieving the precursor slurry, a precursor of aluminum-doped lithium battery cathode material is obtained. The precursor particles have good sphericity and uniform particle size distribution, the aluminum element is uniformly distributed in the precursor, and the tap density of the precursor is greater than 1.5 g / cm 3 , and the specific surface area is 5~60 m 2 / g, and the particle size D50 is 2~20 μm.

[0014] Further defined, the soluble nickel salt in step S1 is one or more of nickel sulfate, nickel nitrate, nickel acetate or nickel chloride; the soluble cobalt salt is one or more of cobalt sulfate, cobalt nitrate, cobalt acetate or cobalt chloride; the soluble manganese salt is one or more of manganese sulfate, manganese nitrate, manganese acetate or manganese chloride.

[0015] Further defined, the alkali solution in step S2 and step S3 is one or more of sodium hydroxide solution or potassium hydroxide solution.

[0016] Further defined, the concentration of the additive in the bottom liquid of the kettle in step S3 is 0.5 - 4 mol / L, and the pH value of the bottom liquid of the kettle is controlled to be 10.0 - 14.0 by adding a complexing agent and an alkali solution.

[0017] Further defined, the total concentration of the mixed metal solution in step S4 is 1.0 - 3.0 mol / L, and the flow rate of the mixed metal solution is 5 - 150 mL / min; the concentration of the aluminum-alkali solution is 0.01 - 5 mol / L, and the flow rate of the aluminum-alkali solution is 5 - 200 mL / min; the concentration of the alkali solution is 2 - 8 mol / L, and the flow rate of the alkali solution is 3 - 150 mL / min; the flow rate of the complexing agent is 0.02 - 100 mL / min.

[0018] Application of the precursor described in the present invention in the preparation of a cathode material for a lithium-ion battery.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention can effectively improve the deposition rate of aluminum element during the coprecipitation process, achieve uniform distribution of aluminum element, and the prepared precursor particles have better sphericity and more uniform particle size distribution. At the same time, the specific surface area of the precursor reaches 5 - 60 m 2 / g, and the tap density is greater than 1.5 g / cm 3, which is beneficial to improving the electrochemical performance and high-capacity long-cycle performance of the cathode material. The solubility product constant of aluminum is quite different from those of nickel, cobalt, and manganese elements, and it is easy to preferentially precipitate to form small particles. In the present invention, two aluminum source materials are selected and fed simultaneously through two feeding methods, replacing the current single aluminum source feeding method. Multiple forms of aluminum ions are introduced into the solution, and additives are added to the bottom solution. On the one hand, it increases the ion saturation in the reaction system, reduces the ion exchange efficiency, and there is a complementary ion effect during the ion exchange process, affecting the exchange effect. On the other hand, it changes the solution ion concentration, affects the diffusion rate, and thus affects the ion precipitation rate, effectively avoiding the generation of small particles. And it effectively ensures that the precursor particles have good sphericity and uniform particle size distribution. The higher specific surface area of the aluminum-doped lithium battery cathode material precursor prepared by the present invention is beneficial to improving the sintering efficiency of the cathode material, accelerating the diffusion of lithium ions during the sintering process, and the larger tap density is beneficial to the production of the cathode electrode sheet, reducing the production cost of secondary batteries. Therefore, the precursor prepared by the present invention not only has excellent spherical morphology and uniform particle size distribution, but also can reduce the production cost and improve the electrochemical performance of the cathode material. In addition, the generation of small balls during the precursor preparation process is not conducive to particle size control and will reduce production efficiency. The present invention adding additives to the bottom solution of the kettle can effectively inhibit the formation of small particle products, is beneficial to regulating the aspect ratio of primary particles and improving sphericity, and at the same time makes the particle size distribution of the precursor particles more uniform. Description of the Drawings

[0020] Figure 1 SEM image of the precursor obtained in Example 1.

[0021] Figure 2 SEM image of the precursor obtained in Example 2.

[0022] Figure 3 SEM image of the precursor obtained in Comparative Example 1.

[0023] Figure 4 SEM image of the precursor obtained in Comparative Example 2.

[0024] Figure 5 SEM image of the precursor obtained in Comparative Example 3.

[0025] Figure 6 SEM image of the precursor obtained in Comparative Example 4. Detailed Embodiments

[0026] The following further elaborates on the above content of the present invention through examples, but it should not be understood that the scope of the above subject matter of the present invention is limited to the following examples. All technologies implemented based on the above content of the present invention belong to the scope of the present invention. Example 1

[0027] The NCA precursor is prepared according to the following method:

[0028] (1) Prepare a mixed metal solution with a total concentration of 1.8 mol / L of nickel sulfate, cobalt sulfate, and aluminum sulfate using pure water, where the molar ratio of nickel, cobalt, and aluminum is 88:8:4; prepare a sodium aluminate solution with a concentration of 1.5 mol / L using a NaOH solution;

[0029] (2) Add pure water, ammonia water, sodium hydroxide solution, and sodium sulfate into the reaction kettle to obtain a mixed solution as the bottom solution of the kettle. The pH of this bottom solution is 13.2, the ammonia concentration is 20 g / L, and the sodium sulfide concentration is 1.2 mol / L;

[0030] (3) Set the stirring rate of the reaction kettle to 300 rpm and control the temperature in the reaction kettle at 40 ± 0.5 °C. Continuously feed the metal mixed solution and the aluminum-alkali solution into the reaction kettle at a ratio of 4:1 by flow rate, and at the same time feed the sodium hydroxide solution and ammonia water to control the pH of the reaction system at 31.2 until the particle size reaches 3.0 - 4.0 μm, then stop feeding into the reaction kettle to obtain the precursor slurry;

[0031] (4) Wash the precursor slurry and dry it at 130 °C for 15 h to obtain the Ni 88 Co5Al7(OH)2 precursor. The sphericity of the particles of this precursor is good and the distribution of aluminum elements is uniform. The particle size distribution of the precursor is uniform and consistent. The tapped density of the precursor is 1.87 g / cm 3 and the specific surface area is 23.43 m 2 / g, and the particle size D50 is 3.5 μm. Example 2

[0032] The NMA precursor is prepared according to the following method:

[0033] (1) Prepare a mixed metal solution with a total concentration of 2 mol / L of nickel sulfate, manganese sulfate, and aluminum sulfate using pure water, where the molar ratio of nickel, manganese, and aluminum is 91:4:5; prepare a sodium aluminate solution with a concentration of 0.1 mol / L using a NaOH solution;

[0034] (2) Add pure water, ammonia water, sodium hydroxide solution, and potassium sulfate into the reaction kettle to obtain a mixed solution as the bottom solution of the kettle. The pH of this bottom solution is 11.6 - 11.7, the ammonia concentration is 3 - 4 g / L, and the potassium sulfate concentration is 1 mol / L;

[0035] (3) Set the stirring rate of the reaction kettle to 800 rpm and control the temperature in the reaction kettle at 40 ± 0.5 °C. Continuously feed the metal mixed solution and the aluminum-alkali solution into the reaction kettle at a flow rate ratio of 1:1. At the same time, feed sodium hydroxide solution and ammonia water to control the pH of the reaction system at 11.6 - 11.7 until the particle size reaches 13.0 - 14.0 μm, and then stop feeding into the reaction kettle to obtain the precursor slurry;

[0036] (4) Wash the precursor slurry and dry it at 100 °C for 15 h to obtain the Ni 93 Mn2Al5(OH)2 precursor. The sphericity of the precursor particles is relatively good and the distribution of aluminum elements is uniform. The particle size distribution of the precursor particles is uniform and consistent. The tapped density of the precursor is 2.12 g / cm 3 , and the specific surface area is 13.47 m 2 / g, and the particle size D50 is 12.4 μm.

[0037] Comparative Example 1

[0038] This comparative example is a control experiment of Example 2, which is carried out under the same conditions and steps as Example 2. The only difference is that only aluminum sulfate is used as the sole aluminum source. The specific method is as follows:

[0039] Prepare the NMA precursor according to the following method:

[0040] (1) Use pure water to prepare a mixed metal solution with a total concentration of 2 mol / L from nickel sulfate, manganese sulfate, and aluminum sulfate, where the molar ratio of nickel, manganese, and aluminum is 91:4:5;

[0041] (2) Add pure water, ammonia water, sodium hydroxide solution, and potassium sulfate into the reaction kettle to obtain a mixed solution as the bottom liquid of the kettle. The pH of this bottom liquid is 11.6 - 11.7, the ammonia concentration is 3 - 4 g / L, and the potassium sulfate concentration is 1 mol / L;

[0042] (3) Set the stirring rate of the reaction kettle to 800 rpm and control the temperature in the reaction kettle at 40 ± 0.5 °C. Continuously feed the metal mixed solution and the aluminum-alkali solution into the reaction kettle at a flow rate ratio of 1:1. At the same time, feed sodium hydroxide solution and ammonia water to control the pH of the reaction system at 11.6 - 11.7 until the particle size reaches 13.0 - 14.0 μm, and then stop feeding into the reaction kettle to obtain the precursor slurry;

[0043] (4) Wash the precursor slurry and dry it at 100 °C for 15 h to obtain the Ni 93 Mn2Al5(OH)2 precursor. The sphericity of this precursor is relatively good, the element distribution is uneven, the particle size distribution of the precursor particles is not uniform and consistent, small particle products are formed, and the tapped density of the precursor is 1.57 g / cm 3, with a specific surface area of 10.24 m 2 / g and a particle size D50 of 12.2 μm.

[0044] Comparative Example 2

[0045] This comparative example is a control experiment for Example 2 and is carried out under the same conditions and steps as Example 2. The only difference is that only the aluminum-alkali solution is used as the sole aluminum source. The specific method is as follows:

[0046] Prepare the NMA precursor according to the following method:

[0047] (1) Prepare a mixed metal solution with a total concentration of 2 mol / L of nickel sulfate and manganese sulfate in pure water, where the molar ratio of nickel to manganese is 95.8:4.2; prepare an aluminum-alkali solution with a concentration of 0.1 mol / L of sodium aluminate in NaOH solution;

[0048] (2) Add pure water, ammonia water, sodium hydroxide solution, and potassium sulfate into the reaction kettle to obtain a mixed solution as the bottom solution of the kettle. The pH of this bottom solution is 11.6 - 11.7, the ammonia concentration is 3 - 4 g / L, and the potassium sulfate concentration is 1 mol / L;

[0049] (3) Set the stirring rate of the reaction kettle to 800 rpm and control the temperature in the reaction kettle at 40 ± 0.5 °C. Continuously feed the metal mixed solution and the aluminum-alkali solution into the reaction kettle at a flow rate ratio of 1:1, and at the same time feed sodium hydroxide solution and ammonia water to control the pH of the reaction system at 11.6 - 11.7 until the particle size reaches 13.0 - 14.0 μm, then stop feeding into the reaction kettle to obtain the precursor slurry;

[0050] (4) Wash the precursor slurry and dry it at 100 °C for 15 h to obtain the Ni 93 Mn2Al5(OH)2 precursor. The sphericity of the precursor particles is uneven, the distribution of aluminum elements is uniform, the particle size distribution of the precursor particles is not uniform, small particle products are formed, and the tap density of the precursor is 1.64 g / cm 3 , with a specific surface area of 12.33 m 2 / g and a particle size D50 of 7.4 μm.

[0051] Comparative Example 3

[0052] This comparative example is a control experiment for Example 2 and is carried out under the same conditions and steps as Example 2. The only difference is that the additive potassium sulfate is not added to the bottom solution. The specific method is as follows:

[0053] (1) Prepare a mixed metal solution with a total concentration of 2 mol / L of nickel sulfate, manganese sulfate, and aluminum sulfate using pure water, where the molar ratio of nickel, manganese, and aluminum is 91:4:5; prepare a sodium aluminate solution with a concentration of 0.1 mol / L using NaOH solution;

[0054] (2) Add pure water, ammonia water, and sodium hydroxide solution into the reaction kettle to obtain a mixed solution as the bottom solution of the kettle. The pH of this bottom solution is 11.6 - 11.7, and the ammonia concentration is 3 - 4 g / L;

[0055] (3) Set the stirring rate of the reaction kettle to 800 rpm and control the temperature in the reaction kettle at 40 ± 0.5 °C. Continuously feed the mixed metal solution and the aluminum-alkali solution into the reaction kettle at a flow rate ratio of 1:1. At the same time, feed sodium hydroxide solution and ammonia water to control the pH of the reaction system at 11.6 - 11.7 until the particle size reaches 13.0 - 14.0 μm, and then stop feeding into the reaction kettle to obtain the precursor slurry;

[0056] (4) Wash the precursor slurry and dry it at 100 °C for 15 h to obtain the Ni 93 Mn2Al5(OH)2 precursor. The sphericity of the particles of this precursor is good and the aluminum element is evenly distributed. The particle size distribution of the precursor is not uniform, forming small particle products. The tap density of the precursor is 1.72 g / cm 3 , and the specific surface area is 12.93 m 2 / g, and the particle size D50 is 13.8 μm.

[0057] Comparative Example 4

[0058] This comparative example is a control experiment of Example 2, which is carried out under the same conditions and steps as Example 2. The only difference is that only aluminum sulfate is used as the sole aluminum source and potassium sulfate as an additive is not added to the bottom solution. The specific method is as follows:

[0059] Prepare the NMA precursor according to the following method:

[0060] (1) Prepare a mixed metal solution with a total concentration of 2 mol / L of nickel sulfate, manganese sulfate, and aluminum sulfate using pure water, where the molar ratio of nickel, manganese, and aluminum is 91:4:5;

[0061] (2) Add pure water, ammonia water, and sodium hydroxide solution into the reaction kettle to obtain a mixed solution as the bottom solution of the kettle. The pH of this bottom solution is 11.6 - 11.7, and the ammonia concentration is 3 - 4 g / L;

[0062] (3) Set the stirring rate of the reactor to 800 rpm and control the temperature inside the reactor at 40 ± 0.5 °C. Continuously feed the metal mixed solution and the aluminum-alkali solution into the reactor at a flow rate ratio of 1:1. At the same time, feed sodium hydroxide solution and ammonia water to control the pH of the reaction system at 11.6 - 11.7 until the particle size reaches 13.0 - 14.0 μm, and then stop feeding into the reactor to obtain the precursor slurry;

[0063] (4) Wash the precursor slurry and dry it at 100 °C for 15 h to obtain the Ni 93 Mn2Al5(OH)2 precursor. The sphericity of the precursor particles is relatively good, the distribution of aluminum elements is uneven, the particle size distribution of the precursor particles is uneven, small particle products are formed, and the tapped density of the precursor is 1.51 g / cm 3 , and the specific surface area is 9.85 m 2 / g, and the particle size D50 is 13.2 μm.

[0064] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a precursor of an aluminum-doped lithium battery cathode material, characterized in that The specific steps are as follows: Step S1: Dissolve the first aluminum salt and the metal salt in pure water to prepare a mixed metal solution, where the first aluminum salt is one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum sol, or sodium aluminate, and the metal salt is one or more of soluble nickel salts, soluble cobalt salts, or soluble manganese salts. The soluble nickel salt is one or more of nickel sulfate, nickel nitrate, nickel acetate, or nickel chloride; the soluble cobalt salt is one or more of cobalt sulfate, cobalt nitrate, cobalt acetate, or cobalt chloride; the soluble manganese salt is one or more of manganese sulfate, manganese nitrate, manganese acetate, or manganese chloride. Step S2: Dissolve the second aluminum salt in an alkali solution to prepare an aluminum-alkali solution, where the second aluminum salt is one or more of aluminum acetate, aluminum sulfate, aluminum chloride, aluminum nitrate, or sodium aluminate, and the alkali solution is one or more of sodium hydroxide solution or potassium hydroxide solution. Step S3: Add pure water, an alkali solution, a complexing agent, and an additive into a reaction kettle to prepare a mixed solution as the bottom liquid of the kettle. The complexing agent is one or more of ammonia water, urea, citric acid, or sodium citrate, the additive is one or more of sodium sulfate, potassium sulfate, or cesium sulfate, and the alkali solution is one or more of sodium hydroxide solution or potassium hydroxide solution. Step S4: The mixed metal solution obtained in step S1, the aluminum-alkali solution obtained in step S2, the alkali solution, and the complexing agent are fed into the reaction kettle in parallel. The pH value of the reaction system is controlled to be 10.0 - 14.0, the rotation speed is 200 - 1000 rpm, and a co-precipitation reaction is carried out at 30 - 90 °C to obtain a precursor slurry. After the precursor slurry is washed, dehydrated, dried, and screened, a lithium-ion battery cathode material precursor doped with aluminum is obtained. The precursor particles have good sphericity and uniform particle size distribution. Aluminum elements are evenly distributed in the precursor, and the tap density of the precursor is greater than 1.5 g / cm 3 , and the specific surface area is 5 - 60 m 2 / g, and the particle size D50 is 2 - 20 μm.

2. The preparation method of the aluminum-doped lithium battery cathode material precursor according to claim 1, characterized in that: In step S3, the concentration of the additive in the bottom liquid of the kettle is 0.5 - 4 mol / L, and the pH value of the bottom liquid of the kettle is controlled to be 10.0 - 14.0 by adding a complexing agent and an alkali solution.

3. The preparation method of the aluminum-doped lithium battery cathode material precursor according to claim 1, wherein: In step S4, the total concentration of the mixed metal solution is 1.0 - 3.0 mol / L, and the flow rate of the mixed metal solution is 5 - 150 mL / min; the concentration of the aluminum-alkali solution is 0.01 - 5 mol / L, and the flow rate of the aluminum-alkali solution is 5 - 200 mL / min; the concentration of the alkali solution is 2 - 8 mol / L, and the flow rate of the alkali solution is 3 - 150 mL / min; the flow rate of the complexing agent is 0.02 - 100 mL / min.

Images