Preparation method of lithium ion battery positive electrode material

Abstract

The invention discloses a preparation method of a lithium ion battery positive electrode material. The method comprises a Couette-Taylor reaction process and a calcining process. The Couette-Taylor reaction process includes feeding a first reaction liquid and a second reaction liquid into a Couette-Taylor reactor, respectively, to form a product stream including a positive electrode material precursor. The first reaction liquid is a multi-metal solution containing a nickel compound, a cobalt compound, and a manganese compound. The second reaction liquid is a lithium source metal solution containing a lithium compound. The positive electrode material precursor has a lithium element. The calcining process comprises the step of calcining the positive electrode material precursor by using a high-temperature tubular furnace to obtain the positive electrode material. The lithium source is introduced through a coprecipitation method, so that the lithium element is uniformly dispersed in the positive electrode material in an atomic hierarchy manner, the mixing degree of cations is reduced, and the orderliness of a layered structure is improved.

Description

Technical Field

[0001] The present invention relates to a method for preparing a cathode material, and more particularly to a method for preparing a cathode material for a lithium-ion battery. Background Art

[0002] The nickel-rich ternary / quaternary cathode material has advantages such as high energy density and low cost, and is the mainstream of the cathode material for lithium-ion batteries at present. The preparation method uses the coprecipitation method to synthesize the cathode material precursor, then mixes it evenly with a lithium salt, and then obtains the cathode material through high-temperature solid-phase sintering. It has the disadvantages of complex process and high preparation cost.

[0003] At present, the lithium salt mixing method mainly adopts the solid-solid grinding and mixing method. First, the lithium salt is loaded into a ball mill for ball milling, and then the micronized lithium salt and the precursor are mixed evenly in a mixer according to a ratio and then sintered.

[0004] Due to the large differences in specific gravity and particle size between the lithium salt and the precursor, it is very difficult to mix the materials evenly by this solid-state mechanical method, resulting in the situation that the sintered oxide is prone to local lithium enrichment or local lithium deficiency, causing problems of poor electrochemical performance and batch-to-batch stability of the product.

[0005] Therefore, how to provide a method for preparing a cathode material for a lithium-ion battery through process and material improvement to overcome the above defects has become one of the important issues to be solved in this field. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing a cathode material for a lithium-ion battery in view of the deficiencies of the prior art, which can make lithium elements evenly dispersed in the cathode material for a lithium-ion battery.

[0007] To solve the above technical problem, one of the technical solutions adopted by the present invention is to provide a method for preparing a cathode material for a lithium-ion battery, which includes: implementing a Couette-Taylor reaction process, including: feeding a first reaction liquid into a Couette-Taylor reactor; wherein the first reaction liquid is a multi-metal solution containing nickel (Ni) compound, cobalt (Co) compound, and manganese (Mn) compound; and feeding a second reaction liquid into the Couette-Taylor reactor to react with the first reaction liquid to form a product stream containing a cathode material precursor; wherein the second reaction liquid is a lithium source metal solution containing lithium (Li) compound; wherein the cathode material precursor has lithium elements; and implementing a calcination process, including: using a high-temperature tubular furnace to calcine the cathode material precursor separated from the product stream to obtain a cathode material.

[0008] Preferably, after the Couette-Taylor reaction process and before the calcination process, the preparation method further includes: implementing a purification process, including: filtering and drying the product stream to separate out the powder of the cathode material precursor, and then performing calcination.

[0009] Preferably, in the second reaction liquid, the lithium compound is at least one of lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium acetate (CH3COOLi), lithium oxalate (Li2C2O4), lithium sulfate (Li2SO4), and lithium nitrate (LiNO3).

[0010] Preferably, in the first reaction liquid, the nickel compound is nickel sulfate (NiSO4), the cobalt compound is cobalt sulfate (CoSO4), and the manganese compound is manganese sulfate (MnSO4).

[0011] Preferably, in the second reaction liquid, the lithium compound is lithium hydroxide (LiOH).

[0012] Preferably, the lithium compound in the second reaction liquid is the source of the lithium element of the cathode material precursor.

[0013] Preferably, during the Couette-Taylor reaction process, the second reaction liquid is configured to regulate the pH value of the reaction mixture containing the first reaction liquid and the second reaction liquid, and the pH value is regulated between pH 10 and pH 12.

[0014] Preferably, during the Couette-Taylor reaction process, the reaction mixture does not contain sodium hydroxide (NaOH).

[0015] Preferably, the Couette-Taylor reaction process further includes: feeding a chelating agent liquid into the Couette-Taylor reactor to mix with the reaction mixture; wherein, the chelating agent liquid is an ammonia water solution.

[0016] Preferably, the flow rate of the first reaction liquid fed into the Couette-Taylor reactor is between 1.5 mL / min and 2.0 mL / min, and the flow rate of the second reaction liquid fed into the Couette-Taylor reactor is between 2.3 mL / min and 3.0 mL / min; wherein, the flow rate ratio between the first reaction liquid flow rate and the second reaction liquid flow rate is between 1:1.2 and 1:2.

[0017] Preferably, the cathode material precursor formed by the Couette-Taylor reaction process is a hydroxide of a metal alloy, and the metal alloy contains nickel element, cobalt element, manganese element, and lithium element.

[0018] Preferably, the calcination conditions of the calcination process are to introduce oxygen into the high-temperature tubular furnace and heat it to a first temperature of 120°C to 180°C, and heat the cathode material precursor for 1 hour to 3 hours; then, heat it to a second temperature of 450°C to 550°C to heat the cathode material precursor for 5 hours to 7 hours; then, heat it to a third temperature of 750°C to 850°C and heat the cathode material precursor for 11 hours to 13 hours to finally form the cathode material.

[0019] Preferably, after the Couette-Taylor reaction process and before the calcination process, the preparation method does not include the steps of mixing and ball-milling the cathode material precursor with a solid lithium salt.

[0020] The beneficial effect of the present invention is that the preparation method of the lithium-ion battery cathode material provided by the present invention can, through the "implementation of the Couette-Taylor reaction process, including: feeding a first reaction liquid into a Couette-Taylor reactor; wherein the first reaction liquid is a multi-metal solution containing nickel (Ni) compounds, cobalt (Co) compounds, and manganese (Mn) compounds; and feeding a second reaction liquid into the Couette-Taylor reactor to react with the first reaction liquid to form a product stream containing a cathode material precursor; wherein, the second reaction liquid is a lithium-source metal solution containing lithium (Li) compounds; wherein, the cathode material precursor has lithium element" and "implementation of the calcination process, including: using a high-temperature tubular furnace to calcine the cathode material precursor separated from the product stream to obtain a cathode material" technical solution, introducing a lithium source through a co-precipitation method, so that lithium elements are uniformly dispersed at the atomic level in the cathode material, thereby reducing the degree of cation mixing and enhancing the orderliness of the layered structure.

[0021] In addition, the particle size of the cathode material is uniform, which helps to improve the battery's endurance and stability. At the same time, on the basis of achieving a high specific capacity and good capacitance retention rate, the safety of the material is also taken into account.

[0022] In order to further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, these descriptions and drawings are only used to illustrate the present invention and do not impose any limitation on the protection scope of the present invention. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the device for preparing the cathode material precursor by using a Couette-Taylor reactor (Couette-Taylor reactors) in the embodiment of the present invention.

[0024] Figure 2The flowchart of the steps for the preparation method of the cathode material of the lithium-ion battery according to the embodiment of the present invention. Detailed implementation manners

[0025] The following are specific embodiments to illustrate the implementation manners of the "preparation method of the cathode material of the lithium-ion battery" disclosed by the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. Additionally, the drawings of the present invention are only for simple schematic illustration and are not drawn according to actual dimensions, which is stated in advance. The following implementation manners will further detail the related technical content of the present invention, but the disclosed content is not used to limit the protection scope of the present invention.

[0026] It should be understood that although terms such as "first", "second", "third", etc. may be used in this article to describe various components or signals, these components or signals should not be limited by these terms. These terms are mainly used to distinguish one component from another, or one signal from another. Additionally, the term "or" used in this article should, depending on the actual situation, may include any one or a combination of more of the associated listed items.

[0027] [Preparation method of cathode material of lithium-ion battery]

[0028] Please refer to Figure 1 and Figure 2 As shown, the embodiment of the present invention provides a preparation method of the cathode material of the lithium-ion battery, which mainly uses Couette-Taylor reactors to prepare the cathode active material precursor, and the cathode active material precursor contains lithium element.

[0029] Then, the cathode active material precursor containing lithium element is directly subjected to subsequent calcination treatment, and it can directly form the cathode material of the lithium-ion battery without the need to be mixed with additional lithium salts.

[0030] The method provided by the embodiment of the present invention can make the lithium element achieve atomic-level dispersion in the cathode material of the lithium-ion battery, and improve the situation of local lithium-rich or lithium-deficient in the prior art, thereby enhancing the endurance and stability of the lithium-ion battery.

[0031] More specifically, the preparation method of the cathode material of the lithium-ion battery according to the embodiment of the present invention includes step S110, step S120, and step S130.

[0032] The step S110 is to implement the Couette-Taylor reaction process, which includes: feeding the first reaction liquid L1 into the Couette-Taylor reactor 1 (such as a continuous Taylor flow reactor, laminar continuous Taylor reactor, LCTR) through the first reaction liquid supply unit 11, and feeding the second reaction liquid L2 into the Couette-Taylor reactor 1 through the second reaction liquid supply unit 12, and performing a co-precipitation reaction to form a product stream P1 containing a precursor of the cathode material with lithium element.

[0033] The first reaction liquid L1 is a multi-metal solution.

[0034] The multi-metal solution contains nickel (Ni) compounds, cobalt (Co) compounds, and manganese (Mn) compounds. In some embodiments of the present invention, the multi-metal solution further contains at least one of magnesium (Mg) compounds and aluminum (Al) compounds.

[0035] For example, the multi-metal solution can be a nickel-cobalt-manganese multi-metal solution, a nickel-cobalt-manganese-magnesium multi-metal solution, or a nickel-cobalt-manganese-aluminum multi-metal solution, but is not limited thereto.

[0036] In some embodiments of the present invention, the nickel compound can be, for example, nickel sulfate (NiSO4), the cobalt compound can be, for example, cobalt sulfate (CoSO4), the manganese compound can be, for example, manganese sulfate (MnSO4), the magnesium compound can be, for example, magnesium sulfate (MgSO4), and the aluminum compound can be, for example, aluminum sulfate (Al2(SO4)3), but the present invention is not limited thereto.

[0037] The second reaction liquid L2 is a lithium source metal solution. The lithium source metal solution contains a lithium (Li) compound.

[0038] In some embodiments of the present invention, the lithium compound is at least one of lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium acetate (CH3COOLi), lithium oxalate (Li2C2O4), lithium sulfate (Li2SO4), and lithium nitrate (LiNO3).

[0039] Preferably, the lithium compound is lithium hydroxide (LiOH).

[0040] The second reaction liquid L2 contains a lithium (Li) compound, which can serve as a source of lithium element for the cathode material precursor in the reaction system. Furthermore, the lithium (Li) compound (such as lithium hydroxide) in the second reaction liquid L2 can serve as a precipitant, which can replace the use of the existing precipitant (that is, sodium hydroxide, NaOH), and the lithium (Li) compound can be used to adjust the pH value of the reaction mixture, such as adjusting it to pH 10 to pH 12, and preferably to pH 10.5 to pH 11.5.

[0041] Overall, the embodiments of the present invention propose a method for preparing a cathode material for a lithium-ion battery. This method utilizes a Couette-Taylor reactor. During the preparation of the precursor, a lithium compound is mixed and precipitated with metal salts such as nickel, cobalt, and manganese through a coprecipitation method. In addition, a crystal nucleus of a multi-metal precursor (such as nickel, cobalt, and manganese) can be first formed from a solution of the multi-metal, and then a lithium source metal solution is introduced to prepare a cathode composite material. The embodiments of the present invention introduce a lithium source through a coprecipitation method, enabling the lithium element to be uniformly dispersed at the atomic level, thereby reducing the degree of cation mixing and enhancing the orderliness of the layered structure. In addition, the generated particle sizes are uniform, which helps to improve the battery's endurance and stability. At the same time, on the basis of achieving a high specific capacity and good capacitance retention rate, the safety of the material is also taken into account.

[0042] More specifically, the Couette-Taylor reactor 1 includes a rotation axis 1a and a reaction cavity 1b that surrounds the rotation axis 1a in the radial direction.

[0043] The starting positions of the Couette-Taylor reactor 1 (such as Figure 1 the position of the left end of the Couette-Taylor reactor 1 in

[0044] are respectively connected to the first reaction liquid supply unit 11, the second reaction liquid supply unit 12, and the chelating agent supply unit 13. The Couette-Taylor reactor 1 further includes a rotation motor 14 connected to the rotation axis 1a in the axial direction, and the rotation motor 14 is configured to drive the rotation axis 1a to rotate along the axial direction. Among them, the first reaction liquid supply unit 11 is configured to feed the first reaction liquid L1 (such as a nickel-cobalt-manganese multi-metal solution) into the reaction cavity 1b of the Couette-Taylor reactor 1 through one of the pump infusion units 151 of the pump module 15.

[0045] Among them, the second reaction liquid supply unit 12 is configured to feed the second reaction liquid L2 (such as a lithium source metal solution) into the reaction cavity 1b of the Couette-Taylor reactor 1 through another pump infusion unit 152 of the pump module 15, mix it with the first reaction liquid L1 to form a reaction mixture, and perform a coprecipitation reaction in the reaction cavity 1b.

[0046] Among them, the chelating agent supply unit 13 is configured to feed a chelating agent liquid L3 (such as an aqueous ammonia solution, NH4OH(aq)) into the reaction cavity 1b of the Couette-Taylor reactor 1 through yet another pump infusion unit 153 of the pump module 15 to mix with the reaction mixture formed by the first reaction liquid L1 (such as a nickel-cobalt-manganese multi-metal solution) and the second reaction liquid L2 (such as a lithium source metal solution), and chelate with these metal elements.

[0047] The rotary motor 14 is configured to drive the rotary axis 1a to rotate along the axial direction, enabling the reaction mixture formed by the first reaction liquid L1 (such as a multi-metal solution), the second reaction liquid L2 (such as a lithium source metal solution), and the chelating agent liquid L3 (such as an aqueous ammonia solution) fed into the reaction cavity 1b of the Couette-Taylor reactor 1 to be mixed evenly and react completely.

[0048] The precursor of the cathode material formed in the Couette-Taylor reaction process has lithium elements dispersed therein, and the lithium elements are evenly dispersed at the atomic level in the precursor of the cathode material.

[0049] During the Couette-Taylor reaction process, the rear side of the discharge port of the Couette-Taylor reactor 1 (such as Figure 1 the rear side of the right end of the Couette-Taylor reactor 1 in the figure) is connected to a pH monitoring unit 16 for monitoring the pH value (such as the pH value) of the product stream P1 containing the precursor of the cathode material.

[0050] In some embodiments of the present invention, in order to improve the reaction efficiency of the Couette-Taylor reaction process, the reaction temperature in the Couette-Taylor reactor 1 is between 50°C and 70°C, and preferably between 55°C and 65°C.

[0051] The motor speed at which the rotary motor 14 drives the rotary axis 1a to rotate is between 500 rpm and 700 rpm, and preferably between 550 rpm and 650 rpm.

[0052] The flow rate of the first reaction liquid L1 (such as a multi-metal solution) fed into the reaction cavity 1b of the Couette-Taylor reactor 1 through the first reaction liquid supply unit 11 is between 1.5 mL / min and 2.0 mL / min, and preferably between 1.6 mL / min and 1.8 mL / min.

[0053] The flow rate of the second reaction liquid L2 (such as a lithium source metal solution) fed into the reaction cavity 1b of the Couette-Taylor reactor 1 through the second reaction liquid supply unit 12 is between 2.3 mL / min and 3.0 mL / min, and preferably between 2.5 mL / min and 2.7 mL / min. It is higher than the flow rate of the first reaction liquid to provide sufficient lithium source. Additionally, the second reaction liquid L2 (such as a lithium source metal solution) can adjust the pH value of the product stream P1 to be between 10 and 12.

[0054] In another aspect, the flow rate ratio between the first reaction liquid flow rate and the second reaction liquid flow rate is between 1:1.2 and 1:2, and preferably between 1:1.4 and 1:1.7.

[0055] Wherein, the total volume molar concentration of the multi-metal (such as nickel-cobalt-manganese) in the first reaction liquid is between 1.5 M and 2.5 M, and preferably between 1.8 M and 2.2 M.

[0056] Wherein, the concentration of the lithium (Li) compound (such as lithium hydroxide) in the second reaction liquid is between 4.5 M and 5.3 M, and preferably between 5 M and 5.3 M.

[0057] The flow rate of the chelating agent liquid L3 (such as an aqueous ammonia solution) fed into the reaction cavity 1b of the Couette-Taylor reactor 1 through the chelating agent supply unit 13 is between 0.4 mL / min and 0.8 mL / min, and the chelating agent flow rate is preferably between 0.5 mL / min and 0.7 mL / min.

[0058] Additionally, the residence time of the reaction mixture formed by the first reaction liquid L1 (such as a multi-metal solution), the second reaction liquid L2 (such as a lithium source metal solution), and the chelating agent liquid L3 (such as an aqueous ammonia solution) in the Couette-Taylor reactor 1 is between 172 minutes and 238 minutes, and preferably between 192 minutes and 217 minutes.

[0059] In the product stream P1, the average particle size (D50) of the cathode material precursor containing lithium element is between 5 microns and 15 microns, and preferably between 7 microns and 12 microns, but the present invention is not limited thereto.

[0060] The precursor of the positive electrode material is a hydroxide of a metal alloy composed of multiple metal elements and lithium element. In some embodiments, the precursor of the positive electrode material is a hydroxide of nickel (Ni)-cobalt (Co)-manganese (Mn)-lithium (Li) alloy, a hydroxide of nickel (Ni)-cobalt (Co)-manganese (Mn)-magnesium (Mg)-lithium (Li) alloy, or a hydroxide of nickel (Ni)-cobalt (Co)-manganese (Mn)-aluminum (Al)-lithium (Li) alloy, but not limited thereto.

[0061] In this embodiment, the position where the second reaction liquid supply unit 12 inputs the second reaction liquid L2 into the Couette-Taylor reactor 1 and the position where the first reaction liquid supply unit 11 inputs the first reaction liquid L1 into the Couette-Taylor reactor 1 are symmetric to each other in the radial direction, so that the first reaction liquid L1 and the second reaction liquid L2 can fully contact with each other, but the present invention is not limited thereto.

[0062] It is worth mentioning that the above process condition parameters listed in this embodiment are the parameters when the volume of the Couette-Taylor reactor is one liter (L), but the present invention is not limited thereto. The volume of the Couette-Taylor reactor can be enlarged to 10 liters to 1000 liters for reaction, and the process condition parameters can be adjusted correspondingly.

[0063] Furthermore, the step S120 is to implement a purification process, including: purifying the product stream P1 containing the precursor of the positive electrode material formed by the Couette-Taylor reactor 1 above to separate the precursor of the positive electrode material from the product stream P1.

[0064] More specifically, the purification process includes: filtering the product stream P1 to filter out the precursor of the positive electrode material, and washing and drying the precursor of the positive electrode material to obtain the purified precursor of the positive electrode material, and its form can be powdery, but the present invention is not limited thereto.

[0065] Furthermore, the step S130 is to implement a calcination process, including: using a high-temperature tubular furnace and introducing oxygen into the high-temperature tubular furnace to calcine the above purified precursor of the positive electrode material, and then obtaining a positive electrode material rich in nickel and lithium, which can be used as the positive electrode material of a lithium battery.

[0066] Among them, the calcination conditions of the calcination process are to heat the oxygen in the high-temperature tubular furnace to a first temperature of 120°C to 180°C and heat the cathode material precursor for 1 hour to 3 hours; heat the oxygen in the high-temperature tubular furnace to a second temperature of 450°C to 550°C and heat the cathode material precursor for 5 hours to 7 hours; then, heat the oxygen in the high-temperature tubular furnace to a third temperature of 750°C to 850°C and heat the cathode material precursor for 11 hours to 13 hours, thereby finally forming the above-mentioned nickel-rich and lithium-rich cathode material. However, the calcination process of the present invention is not limited to the above conditions.

[0067] It is worth mentioning that, in this embodiment, since the cathode material precursor formed by the Couette-Taylor reaction process is a hydroxide of an alloy of multiple metal elements and lithium element, the calcination process can directly calcine the purified cathode material precursor using a high-temperature tubular furnace, and thus the steps of mixing and ball milling the precursor with a solid lithium salt (such as solid lithium hydroxide) can be omitted.

[0068] According to the above configuration, the embodiment of the present invention uses a novel Taylor reactor to replace the traditional continuous stirred reactor and uses the co-precipitation method to prepare the cathode material precursor. By adjusting the reaction temperature, rotation speed and liquid flow rate, the particle size, crystallinity and specific surface area of the precursor are controlled, which is suitable for industrial continuous production. In addition, the embodiment of the present invention introduces a lithium source into the multi-metal precursor by the co-precipitation method, replacing the existing method of introducing the lithium source by mixing and grinding, so that the lithium element is uniformly dispersed at the atomic level. The method of the embodiment of the present invention can omit the steps of mixing and ball milling and has the advantage of simple process.

[0069] [Advantages of the embodiment]

[0070] The beneficial effects of the present invention are as follows. The preparation method of the cathode material for lithium-ion batteries provided by the present invention can be achieved through "implementing the Couette-Taylor reaction process, including: feeding a first reaction liquid into a Couette-Taylor reactor; wherein the first reaction liquid is a multi-metal solution containing nickel (Ni) compounds, cobalt (Co) compounds, and manganese (Mn) compounds; and feeding a second reaction liquid into the Couette-Taylor reactor to react with the first reaction liquid to form a product stream containing a cathode material precursor; wherein the second reaction liquid is a lithium-source metal solution containing lithium (Li) compounds; and wherein the cathode material precursor contains lithium element" and "implementing a calcination process, including: using a high-temperature tubular furnace to calcine the cathode material precursor separated from the product stream to obtain a cathode material". By introducing the lithium source through the co-precipitation method, lithium elements are uniformly dispersed at the atomic level in the cathode material, thereby reducing the degree of cation mixing and enhancing the orderliness of the layered structure. In addition, the generated particle sizes are uniform, which helps to improve the battery's endurance and stability. At the same time, on the basis of achieving a high specific capacity and good capacitance retention rate, the material safety is also taken into account.

[0071] The above are only the preferred feasible embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent changes and modifications made according to the claims of the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a positive electrode material for a lithium ion battery, characterized in that: The preparation method of the lithium ion battery positive electrode material comprises: Implement the Couette-Taylor reaction process, including: Feeding a first reaction liquid into a Couette-Taylor reactor; wherein the first reaction liquid is a multi-metal solution comprising: a nickel compound, a cobalt compound, and a manganese compound; and Feeding a second reaction liquid into the Couette-Taylor reactor to react with the first reaction liquid to form a product stream containing a cathode material precursor; wherein the second reaction liquid is a lithium source metal solution containing a lithium compound; wherein the cathode material precursor has a lithium element; and The calcination process is implemented, comprising: using a high-temperature tubular furnace to calcine the cathode material precursor separated from the product stream to obtain a cathode material.

2. The method for preparing a positive electrode material for a lithium ion battery according to claim 1, characterized in that: After the Couette-Taylor reaction process and before the calcination process, the preparation method further includes: performing a purification process, including: filtering and drying the product flow to separate the powder of the positive electrode material precursor, and then calcining.

3. The method for preparing a positive electrode material for a lithium ion battery according to claim 1, characterized in that: In the second reaction liquid, the lithium compound is at least one of lithium hydroxide, lithium carbonate, lithium acetate, lithium oxalate, lithium sulfate, and lithium nitrate.

4. The method for preparing a positive electrode material for a lithium ion battery according to claim 1, characterized in that: In the first reaction liquid, the nickel compound is nickel sulfate, the cobalt compound is cobalt sulfate, and the manganese compound is manganese sulfate.

5. The method for preparing a positive electrode material for a lithium ion battery according to claim 1, characterized in that: In the second reaction liquid, the lithium compound is lithium hydroxide.

6. The method for preparing a positive electrode material for a lithium ion battery according to claim 5, characterized in that: The lithium compound in the second reaction liquid is the source of the lithium element of the positive electrode material precursor.

7. The method for preparing a positive electrode material for a lithium ion battery according to claim 6, characterized in that: During the Couette-Taylor reaction, the second reaction liquid is configured to adjust the pH value of the reaction mixture including the first reaction liquid and the second reaction liquid, and the pH value is adjusted between pH 10 and pH 12.

8. The method for preparing a positive electrode material for a lithium ion battery according to claim 7, characterized in that: During the Couette-Taylor reaction, the reaction mixture does not contain sodium hydroxide.

9. The method for preparing a positive electrode material for a lithium ion battery according to claim 7, characterized in that: The Couette-Taylor reaction process also includes: A chelating agent liquid is fed into the Couette-Taylor reactor to mix with the reaction mixture; wherein the chelating agent liquid is an aqueous ammonia solution.

10. The method for preparing a positive electrode material for a lithium ion battery according to claim 1, characterized in that: The first reaction liquid flow rate of the first reaction liquid fed into the Couette-Taylor reactor is between 1.5 ml / min and 2.0 ml / min, and the second reaction liquid flow rate of the second reaction liquid fed into the Couette-Taylor reactor is between 2.3 ml / min and 3.0 ml / min; wherein the flow ratio between the first reaction liquid flow rate and the second reaction liquid flow rate is between 1:1.2 and 1:

2.

11. The method for preparing a positive electrode material for a lithium ion battery according to claim 1, characterized in that: The positive electrode material precursor formed by the Couette-Taylor reaction process is a hydroxide of a metal alloy, and the metal alloy contains nickel, cobalt, manganese, and lithium.

12. The method for preparing a positive electrode material for a lithium ion battery according to claim 1, characterized in that: The calcination conditions of the calcination process are as follows: oxygen is introduced into the high-temperature tubular furnace, and the positive electrode material precursor is heated to a first temperature of 120°C to 180°C for 1 to 3 hours; then, the positive electrode material precursor is heated to a second temperature of 450°C to 550°C for 5 to 7 hours; then, the positive electrode material precursor is heated to a third temperature of 750°C to 850°C for 11 to 13 hours to finally form the positive electrode material.

13. The method for preparing a positive electrode material for a lithium ion battery according to claim 1, characterized in that: After the Couette-Taylor reaction process and before the calcination process, the preparation method does not include the steps of mixing and ball milling the positive electrode material precursor and the solid lithium salt.

Images