A method for preparing a small-particle nickel-cobalt-manganese ternary precursor using a narrow-particle continuous method

Abstract

The present invention relates to the technical field of battery positive electrode materials. The method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous method of the present invention increases the grain size step by step by setting up a multi-stage reactor. The pH value of the second to fifth-stage reactors during the liquid spraying process is lower than the pH value of the seed reactor. In this way, the generation of new crystal nuclei can be significantly reduced, thereby controlling the concentration of the grains in the reactor. Since the smaller the grain concentration, the more uniform the particle size distribution of the grains. At the same time, the step-by-step synthesis of the precursor can enable continuous production. Therefore, compared with the prior art, the present invention can not only ensure non-stop production, but also reduce the generation of small particles, so that the nickel-cobalt-manganese precursor has a narrow particle size distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of battery positive electrode materials, and in particular to a method for preparing a small-particle nickel-cobalt-manganese ternary precursor using a narrow-particle continuous method. Background Art

[0002] Compared to traditional methods for preparing nickel-cobalt-manganese ternary precursors, the continuous process offers higher yields. However, due to production mode and pH fluctuations, it is prone to producing fine powder and small particles. These factors result in a wide particle size distribution of the resulting precursor: (D90-D10) / D50>0.7, which fails to meet customer needs. Excessive small particles can also lead to overheating during battery production, affecting battery capacity.

[0003] Existing methods for achieving a narrow particle size distribution primarily involve co-precipitation to prepare the precursor. During the preparation process, the pH value is controlled to achieve a controlled rate. Each time the kettle fills, the supernatant is pumped out, followed by spraying, and this cycle is repeated until the particle size reaches the target. This method, a batch-process precursor preparation method, can achieve a narrow crystal nucleus particle size distribution. However, due to the repeated precipitation and supernatant pumping, production efficiency is low.

[0004] Patent No. 202211144581.7, titled "A Narrow Particle Size Distribution and Small Particle Size Nickel-Cobalt-Manganese Ternary Precursor, Preparation Method, and Lithium-Ion Battery," utilizes a solution that involves turning on a thickener for full reflux after 4 to 12 hours of reaction, achieving the goal of producing a product with a narrow particle size distribution. However, the thickener used in this solution is expensive, prone to clogging over long periods of use, difficult to clean, and has a long cycle time, impacting production schedules.

[0005] The patent number is 202110569383.4, and the name is "A nickel cobalt manganese hydroxide and its preparation method". The scheme adopted can synthesize a composite precursor product with controllable particle size distribution, good sphericity of large, medium and small particles and consistent morphology; and, the entire synthesis process does not require stopping the reaction midway, can grow continuously, and has a large output, but the particle size distribution diameter K90 = (D90-D10) / D50 is still between 1.00 and 1.50. During the synthesis process, due to the continuous increase in the solid content in the reaction system, small particles are inevitably produced, resulting in a wider particle size distribution. The produced overly small particles still exist in the prepared positive electrode material, which is more prone to overcharge or over-discharge, seriously affecting the specific capacity and cycle performance of the material. The commonly used method to reduce the generation of small particles is to reduce the solid content of the reactor synthesis by stopping the reactor and dividing the material, but this method seriously affects production capacity, resulting in low synthesis capacity, reduced production efficiency, and increased costs. Summary of the Invention

[0006] In view of this, it is necessary to provide a method for preparing a nickel-cobalt-manganese precursor that can meet the requirements of both high production capacity and narrow particle size distribution.

[0007] A method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous process comprises the following steps:

[0008] Step S1, preparing raw materials:

[0009] Prepare a soluble nickel-cobalt-manganese mixed solution of predetermined concentration for use;

[0010] Prepare a predetermined concentration of soluble ammonia water as a complexing agent for use:

[0011] A sodium hydroxide solution of a predetermined concentration is prepared for use as a precipitant;

[0012] Step S2: adding pure water, a predetermined amount of ammonia water, and sodium hydroxide solution into the seed reactor to prepare a base solution, wherein the pH of the base solution is 12.2-12.9 and the ammonia concentration is 0.2-0.4 mol / L;

[0013] Step S3: Stirring the seed reactor at a rate of 40-200 rpm, introducing protective gas into the seed reactor to expel oxygen from the reaction system;

[0014] Step S4, adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution to the seed reactor in parallel in the form of a spray, wherein the pH during the reaction is 12.0-12.5, the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min, and the ammonia concentration is 0.2-0.4 mol / L;

[0015] Step S5: When the seed reactor is full of liquid, the liquid is separated into several secondary reactors respectively. At the same time, the secondary reactor is stirred at a rate of 40-200 r / min, and protective gas is introduced into the secondary reactor to exhaust oxygen in the reaction system. At the same time, the seed reactor continues to spray liquid to continue to form new crystal nuclei;

[0016] Step S6, when a predetermined amount of material enters the secondary reactor, the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution are added to the secondary reactor in parallel in the form of a spray to allow the crystal nuclei to continue growing. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min;

[0017] Step S7: When the secondary reactor is full of liquid, the liquid overflows into the tertiary reactor A. After the tertiary reactor A is full of liquid, the secondary reactor turns to the tertiary reactor B to overflow the liquid. After the tertiary reactor B is full of liquid, the secondary reactor turns to the tertiary reactor A to overflow the liquid, and the cycle continues.

[0018] Step S8: extracting the supernatant from the tertiary reactor A, then starting stirring in the tertiary reactor A at a stirring rate of 40-200 r / min, and introducing protective gas into the tertiary reactor A to exhaust oxygen from the reaction system, and adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution to the tertiary reactor A in parallel in the form of a spray to allow continuous grain growth. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min.

[0019] Step S9, when the third-stage reactor A is full of liquid, the liquid overflows into the fourth-stage reactor A until the fourth-stage reactor A is full of liquid, and then the third-stage reactor A stops spraying liquid;

[0020] Step S10: extracting the supernatant from the fourth-stage reactor A, starting stirring in the fourth-stage reactor A at a stirring rate of 40-200 r / min, and introducing protective gas into the fourth-stage reactor A to exhaust oxygen in the reaction system. The prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution are added to the fourth-stage reactor A in parallel in the form of a spray to allow continuous grain growth. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min.

[0021] Step S11, when the fourth-stage reactor A is full of liquid, the liquid overflows into the fifth-stage reactor A until the fifth-stage reactor A is full of liquid, and then the fifth-stage reactor A stops spraying liquid;

[0022] Step S12: extracting the supernatant from the fifth-stage reactor A, starting stirring in the fifth-stage reactor A at a stirring rate of 40-200 r / min, introducing a protective gas into the fifth-stage reactor A to exhaust oxygen from the reaction system, and adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution to the fifth-stage reactor A in parallel in the form of a spray to allow continuous grain growth. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min.

[0023] Step S13: When the particle size of the liquid in the third-stage reactor A, the fourth-stage reactor A, and the fifth-stage reactor A meets the expectation, all the liquid is discharged to the next process, so that the third-stage reactor A, the fourth-stage reactor A, and the fifth-stage reactor A are in an empty state;

[0024] Step S14, repeat steps S7 to S13.

[0025] Beneficial effects: The method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous method of the present invention increases the grain size step by step by setting a multi-stage reactor. The pH of the second to fifth-stage reactors is lower than the pH value of the seed reactor during the liquid spraying process. In this way, the generation of new crystal nuclei can be significantly reduced, thereby controlling the concentration of the grains in the reactor. Since the smaller the grain concentration, the more uniform the particle size distribution of the grains. At the same time, the step-by-step synthesis of the precursor can enable continuous production. Therefore, compared with the prior art, the present invention can not only continue production without stopping, but also reduce the generation of small particles, so that the nickel-cobalt-manganese precursor has a narrow particle size distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a process flow chart of the method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous method.

[0027] Figure 2 This is a material flow diagram of a preferred embodiment of the method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous method of the present invention.

[0028] Figure 3 This is an electron microscope image of the precursor prepared by the method for preparing a small-particle nickel-cobalt-manganese ternary precursor using a narrow-particle continuous method of the present invention. DETAILED DESCRIPTION

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Please see Figure 1 A method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous method comprises the following steps:

[0031] Step S1, preparing raw materials:

[0032] Prepare a soluble nickel-cobalt-manganese mixed solution of predetermined concentration for use;

[0033] Prepare a predetermined concentration of soluble ammonia water as a complexing agent for use:

[0034] A sodium hydroxide solution of a predetermined concentration is prepared for use as a precipitant;

[0035] Step S2: adding pure water, a predetermined amount of ammonia water, and sodium hydroxide solution into the seed reactor to prepare a base solution, wherein the pH of the base solution is 12.2-12.9 and the ammonia concentration is 0.2-0.4 mol / L;

[0036] The amount of pure water, ammonia water and sodium hydroxide solution added depends on the actual situation, as long as the pH of the base solution is 12.2-12.9 and the ammonia concentration is 0.2-0.4 mol / L.

[0037] Step S3: Stirring the seed reactor at a rate of 40-200 rpm, introducing protective gas into the seed reactor to expel oxygen from the reaction system;

[0038] Step S4, adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution in parallel in the form of a spray into the seed reactor, the pH during the reaction is 12.0-12.5, the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min, and the ammonia concentration is 0.2-0.4 mol / L; this process is mainly the process of generating crystal nuclei, and the growth of the crystal nuclei is carried out in the secondary reactor to the fifth reactor.

[0039] Step S5: When the seed reactor is full of liquid, the liquid is separated into several secondary reactors respectively. At the same time, the secondary reactor is stirred at a rate of 40-200 r / min, and protective gas is introduced into the secondary reactor to exhaust oxygen in the reaction system. At the same time, the seed reactor continues to spray liquid to continue to form new crystal nuclei;

[0040] Step S6, when a predetermined amount of material enters the secondary reactor, the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution are added to the secondary reactor in parallel in the form of a spray to allow the crystal nuclei to continue growing. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min;

[0041] Step S7: When the secondary reactor is full of liquid, the liquid overflows into the tertiary reactor A. After the tertiary reactor A is full of liquid, the secondary reactor turns to the tertiary reactor B to overflow the liquid. After the tertiary reactor B is full of liquid, the secondary reactor turns to the tertiary reactor A to overflow the liquid, and the cycle continues.

[0042] Step S8: extracting the supernatant from the tertiary reactor A, then starting stirring in the tertiary reactor A at a stirring rate of 40-200 r / min, and introducing protective gas into the tertiary reactor A to exhaust oxygen from the reaction system, and adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution to the tertiary reactor A in parallel in the form of a spray to allow continuous grain growth. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min.

[0043] Step S9, when the third-stage reactor A is full of liquid, the liquid overflows into the fourth-stage reactor A until the fourth-stage reactor A is full of liquid, and then the third-stage reactor A stops spraying liquid;

[0044] Step S10: extracting the supernatant from the fourth-stage reactor A, then starting stirring in the fourth-stage reactor A at a stirring rate of 40-200 r / min, and introducing protective gas into the fourth-stage reactor A to exhaust oxygen in the reaction system, and adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution to the fourth-stage reactor A in parallel in the form of a spray to allow continuous grain growth. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min;

[0045] Step S11, when the fourth-stage reactor A is full of liquid, the liquid overflows into the fifth-stage reactor A until the fifth-stage reactor A is full of liquid, and then the fifth-stage reactor A stops spraying liquid;

[0046] Step S12: extracting the supernatant from the fifth-stage reactor A, starting stirring in the fifth-stage reactor A at a stirring rate of 40-200 r / min, introducing a protective gas into the fifth-stage reactor A to exhaust oxygen from the reaction system, and adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution to the fifth-stage reactor A in parallel in the form of a spray to allow continuous grain growth. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min.

[0047] Step S13: When the particle size of the liquid in the third-stage reactor A, the fourth-stage reactor A, and the fifth-stage reactor A meets the expectation, all the liquid is discharged to the next process, so that the third-stage reactor A, the fourth-stage reactor A, and the fifth-stage reactor A are in an empty state;

[0048] Step S14, repeat steps S7 to S13.

[0049] The process from the secondary reactor to the fifth reactor is the gradual growth of the crystal nucleus. The difference between the secondary reactor and the subsequent reactor is that the liquid in the secondary reactor is not obtained by overflow, so there is no static precipitation, it is always in a stirring state, and the crystals are suspended in the liquid. In a preferred embodiment, there are two tertiary reactors, namely, tertiary reactor A and tertiary reactor B. The secondary reactor supplies liquid to the two tertiary reactors in turn. In the subsequent reaction process, there is always a tertiary reactor and the subsequent 4th reactor and 5th reactor in an empty reactor state. Two groups of 3rd reactors, 4th reactor and 5th reactor take turns to prepare precursors. The seed reactor and the first reactor are always in a continuous working state, and there is no need to repeatedly start the reactor, which reduces the use of bottom liquid.

[0050] Furthermore, in step S1, the concentration of the soluble nickel-cobalt-manganese mixed solution is 1.5-3.0 mol / L.

[0051] In a preferred embodiment, the soluble nickel-cobalt-manganese mixed solution is a solution of nickel sulfate, cobalt sulfate and manganese sulfate.

[0052] In another preferred embodiment, the soluble nickel-cobalt-manganese mixed solution is a solution of nickel nitrate, cobalt nitrate and manganese nitrate.

[0053] In another preferred embodiment, the soluble nickel-cobalt-manganese mixed solution is a solution of nickel chloride, cobalt chloride and manganese chloride.

[0054] In a preferred embodiment, in step S2, the volume of the seed reactor is 5000 L, and the amount of pure water added is 2000 L.

[0055] like Figure 2 As shown, in a preferred embodiment, the implementation process of the present invention is as follows:

[0056] The seed reactor produces feed liquid 1 containing crystal nuclei through steps 2 to 4. After filling the seed reactor, feed liquid 1 enters the two secondary reactors. During this process, the seed reactor continuously sprays liquid, continuously producing new crystal nuclei. The volume of feed liquid 1 and the concentration of crystal nuclei within the seed reactor reach a dynamic equilibrium, allowing the seed reactor to continuously provide a stable concentration of feed liquid 1 to the two secondary reactors. After entering the two secondary reactors, feed liquid 1 is sprayed, causing the particle size to increase again. Due to the lowered pH during the reaction, the number of new crystal nuclei is significantly reduced. In the secondary reactors, crystal growth primarily occurs, resulting in a more uniform particle size. As the spraying continues, feed liquid 2 in the secondary reactor increases until it fills the reactor. Feed liquid 2 then overflows from the two secondary reactors and enters tertiary reactors A and C, respectively. For example, when tertiary reactor A is filled with feed liquid 2, gravity separates the solid and liquid components of feed liquid 2, and the supernatant is discharged, concentrating feed liquid 2. After that, the tertiary reactor A continues to spray liquid, and the grains continue to grow, and the number of grains remains basically unchanged. During the spraying process of the tertiary reactor A, the liquid 2 of the secondary reactor turns to overflow into the tertiary reactor B. Since the volume of the reactor is relatively large and the overflow speed is slow, the tertiary reactor B is in the overflow period. The tertiary reactor A and the subsequent tertiary reactor A and the fifth reactor A continue to react until the reaction is completed. The tertiary reactor A, the fourth reactor A, and the fifth reactor A have all discharged their liquids. At this time, the tertiary reactor B is filled with liquid 2. The tertiary reactor B, the fourth reactor B, and the fifth reactor B repeat the process of the tertiary reactor A, the fourth reactor A, and the fifth reactor A. Since the liquid 2 overflows into the tertiary reactor A, it will undergo static separation, thereby producing a supernatant. After the liquid 2 fills the tertiary reactor A, the tertiary reactor discharges the supernatant. Afterward, the third-stage reactor A continues to spray liquid to form liquid 3, gradually raising the liquid level until liquid 3 fills the third-stage reactor A and overflows into the fourth-stage reactor A. When the fourth-stage reactor A is filled with liquid 3, the third-stage reactor A stops spraying liquid, effectively stopping the overflow. The fourth-stage reactor A then remains stationary, allowing solid-liquid separation. The supernatant is then discharged from the fourth-stage reactor A and sprayed again to form liquid 4, allowing the grains to continue growing. The third-stage reactor A is constantly stirred, preventing the grains from settling. During the spraying process, the third-stage reactor A also sprays liquid, which overflows into the fourth-stage reactor A. Since the third and fourth-stage reactors A spray liquid almost simultaneously, the grains grow synchronously. When the fourth-stage reactor A is filled with liquid 4, liquid 4 overflows into the fifth-stage reactor A until liquid 4 fills the fifth-stage reactor A, at which point the third- and fourth-stage reactors A stop spraying liquid. After the liquid in the fifth-stage reactor A is filled, supernatant will also be produced. After the supernatant is discharged, the third-stage reactor A, the fourth-stage reactor A, and the fifth-stage reactor A will spray liquid synchronously to allow the grains to continue to grow until the grains meet the requirements and the spraying is stopped.The liquid in the third, fourth, and fifth reactors is then drained and transferred to the next process. Specifically, the liquid undergoes filtration, centrifugation, drying, demagnetization, screening, and packaging. The resulting precursor is shown in the following electron micrograph. Figure 3 As shown, the particle size of the precursor is relatively uniform. The particle size distribution of different batches of precursors is shown in Table 1:

[0057] Table 1: Particle size test data of the precursor prepared by the present invention:

[0058]

[0059]

[0060] At the same time, Table 2 also gives the particle size distribution test data of different batches of precursors prepared by the intermittent method.

[0061] batch D10(um) D50(um) D90(um) Particle size distribution 1 2.321 3.331 4.605 0.688 2 2.267 3.278 4.552 0.697 3 2.064 3.049 4.300 0.733 4 2.283 3.278 4.472 0.668 5 2.140 3.305 4.409 0.687 6 2.271 3.337 4.765 0.747 7 2.146 3.431 4.627 0.723 8 2.433 3.462 4.837 0.694

[0062] From the comparison between Table 1 and Table 2, it can be seen that the particle size distribution of the precursor prepared by the present invention is significantly smaller than that of the precursor prepared by the batch method.

[0063] The above disclosure is only a preferred embodiment of the present invention, and it is certainly not intended to limit the scope of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous process, characterized in that: The following steps are involved: Step S1, preparing raw materials: Prepare a soluble nickel-cobalt-manganese mixed solution of predetermined concentration for use; Prepare a predetermined concentration of soluble ammonia water as a complexing agent for use: A sodium hydroxide solution of a predetermined concentration is prepared for use as a precipitant; Step S2: adding pure water, a predetermined amount of ammonia water, and sodium hydroxide solution into the seed reactor to prepare a base solution, wherein the pH of the base solution is 12.2-12.9 and the ammonia concentration is 0.2-0.4 mol / L; Step S3: Stirring the seed reactor at a rate of 40-200 rpm, introducing protective gas into the seed reactor to expel oxygen from the reaction system; Step S4, adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution to the seed reactor in parallel in the form of a spray, wherein the pH during the reaction is 12.0-12.5, the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min, and the ammonia concentration is 0.2-0.4 mol / L; Step S5: When the seed reactor is full of liquid, the liquid is separated into several secondary reactors respectively. At the same time, the secondary reactor is stirred at a rate of 40-200 r / min, and protective gas is introduced into the secondary reactor to exhaust oxygen in the reaction system. At the same time, the seed reactor continues to spray liquid to continue to form new crystal nuclei; Step S6, when a predetermined amount of material enters the secondary reactor, the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution are added to the secondary reactor in parallel in the form of a spray to allow the crystal nuclei to continue growing. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min; Step S7: When the secondary reactor is full of liquid, the liquid overflows into the tertiary reactor A. After the tertiary reactor A is full of liquid, the secondary reactor turns to the tertiary reactor B to overflow the liquid. After the tertiary reactor B is full of liquid, the secondary reactor turns to the tertiary reactor A to overflow the liquid, and the cycle continues. Step S8: extracting the supernatant from the tertiary reactor A, then starting stirring in the tertiary reactor A at a stirring rate of 40-200 r / min, and introducing protective gas into the tertiary reactor A to exhaust oxygen from the reaction system, and adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution to the tertiary reactor A in parallel in the form of a spray to allow continuous grain growth. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min. Step S9, when the third-stage reactor A is full of liquid, the liquid overflows into the fourth-stage reactor A until the fourth-stage reactor A is full of liquid, and then the third-stage reactor A stops spraying liquid; Step S10: extracting the supernatant from the fourth-stage reactor A, starting stirring in the fourth-stage reactor A at a stirring rate of 40-200 r / min, and introducing protective gas into the fourth-stage reactor A to exhaust oxygen in the reaction system. The prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution are added to the fourth-stage reactor A in parallel in the form of a spray to allow continuous grain growth. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min. Step S11, when the fourth-stage reactor A is full of liquid, the liquid overflows into the fifth-stage reactor A until the fifth-stage reactor A is full of liquid, and then the fifth-stage reactor A stops spraying liquid; Step S12: extracting the supernatant from the fifth-stage reactor A, starting stirring in the fifth-stage reactor A at a stirring rate of 40-200 r / min, introducing a protective gas into the fifth-stage reactor A to exhaust oxygen from the reaction system, and adding the prepared nickel-cobalt-manganese mixed solution, ammonia water, and sodium hydroxide solution to the fifth-stage reactor A in parallel in the form of a spray to allow continuous grain growth. The pH during the reaction is 11.0-11.5, and the flow rate of the nickel-cobalt-manganese mixed solution is 2-5 L / min. Step S13: When the particle size of the liquid in the third-stage reactor A, the fourth-stage reactor A, and the fifth-stage reactor A meets the expectation, all the liquid is discharged to the next process, so that the third-stage reactor A, the fourth-stage reactor A, and the fifth-stage reactor A are in an empty state; Step S14, repeat steps S7 to S13.

2. The method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous process according to claim 1, characterized in that: In step S1, the concentration of the soluble nickel-cobalt-manganese mixed solution is 1.5-3.0 mol / L.

3. The method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous process according to claim 1, characterized in that: The soluble nickel-cobalt-manganese mixed solution is a solution of nickel sulfate, cobalt sulfate and manganese sulfate.

4. The method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous process according to claim 1, characterized in that: The soluble nickel-cobalt-manganese mixed solution is a solution of nickel nitrate, cobalt nitrate and manganese nitrate.

5. The method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous process according to claim 1, characterized in that: The soluble nickel-cobalt-manganese mixed solution is a solution of nickel chloride, cobalt chloride and manganese chloride.

6. The method for preparing a small-particle nickel-cobalt-manganese ternary precursor by a narrow-particle continuous process according to claim 1, characterized in that: In step S2, the volume of the seed reactor is 5000 L, and the amount of pure water added is 2000 L.

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