High-nickel precursor and preparation method thereof

Abstract

The invention discloses a preparation method of a high-nickel precursor. The preparation method comprises the following steps: step 1, preparing an alkali solution, an ammonia solution and a mixed salt solution containing nickel, cobalt and manganese; step 2, adding a base solution into the reaction kettle; 3, introducing protective gas into a reaction kettle, adding the mixed salt solution, the alkali solution and the ammonia solution into the reaction kettle, and carrying out precipitation reaction to obtain precipitation particles; the precipitation reaction comprises three stages, the reaction is sequentially a nucleation stage, a first growth stage and a second growth stage, the pH values of reaction systems corresponding to the three stages are sequentially pH0, pH1 and pH2, and pH0 is larger than or equal to 0 and smaller than or equal to pH2; and step 4, stopping feeding when the particle size D50 of the precipitate particles is detected to reach the target particle size, aging, and carrying out post-treatment to obtain the high-nickel precursor. According to the preparation method disclosed by the invention, the high-nickel precursor with high crystallinity, low sodium-sulfur content and controllable BET and morphology can be obtained. The invention further discloses the high-nickel precursor.

Description

Technical Field

[0001] The present invention belongs to the technical field of precursors for lithium battery cathode materials, and particularly relates to a high-nickel precursor and a preparation method thereof. Background Art

[0002] In recent years, the new energy industry has developed rapidly, promoting the booming development of batteries and upstream products. Electric vehicles are an important battleground for competition between ternary lithium batteries and lithium iron phosphate batteries. As the power battery that accounts for 40% of the cost of new energy vehicles, its product performance, reliability, cruising range, lifespan, etc. determine the development of new energy vehicles. Ternary lithium batteries and lithium iron phosphate batteries each have their own advantages and disadvantages. The former has outstanding product performance and cruising range, while the latter has outstanding advantages in safety reliability and long cycle life. Ternary batteries are the key to solving the main bottleneck of "range anxiety" that plagues the development of new energy vehicles.

[0003] The higher the nickel content in the ternary material, the more electrons are transferred, the higher the capacity, and the higher the energy density of the corresponding battery module. For long-range new energy vehicles, high-nickel materials are an inevitable choice. In the future, with the continuous introduction of models with extremely long cruising ranges, high-nickel ternary lithium batteries will see a significant increase in production. High-nickel 8-series, high-nickel 9-series, and even cobalt-free cathode materials will become the mainstream direction of future market development due to their advantages of low cost and high energy density.

[0004] In recent years, the trend of high nickel has become increasingly obvious. The advantages of high-nickel materials such as low cost and high capacity are the main development directions of next-generation new energy battery materials. On the one hand, in terms of production capacity, the production efficiency per ton of products is improved; on the other hand, in terms of process, the production cost per ton is reduced; at the same time, it is also necessary to conduct customized development of products according to the characteristics of the products and the application fields. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technologies mentioned above, the purpose of the present invention is to provide a high-nickel precursor with high crystallinity, low sodium and sulfur content, controllable BET and morphology, and a preparation method thereof. To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A preparation method of a high-nickel precursor, comprising the following steps:

[0007] Step 1: Prepare an alkali solution, an ammonia solution, and a mixed salt solution containing nickel, cobalt, and manganese;

[0008] Step 2: Add a bottom liquid to the reaction kettle;

[0009] Step 3: Introduce a protective gas into the reactor, and add the mixed salt solution, the alkali solution, and the ammonia solution into the reactor to carry out a precipitation reaction to obtain precipitate particles; the precipitation reaction includes three stages, which are successively the nucleation stage, the first growth stage, and the second growth stage as the reaction proceeds. The pH values of the reaction systems corresponding to the three stages are pH0, pH1, and pH2 respectively, and pH0 ≤ pH1 ≤ pH2;

[0010] Step 4: Stop feeding when it is detected that the particle size D50 of the precipitate particles reaches the target particle size, and obtain a high-nickel-type precursor through post-treatment after aging.

[0011] Further, in Step 1, the molar concentration of the mixed salt solution is 1.0 - 3.0 mol / L, the molar concentration of the alkali solution is 4.0 - 11.0 mol / L, and the mass concentration of the ammonia solution is 8.0 - 12%.

[0012] Further, in Step 2, the bottom liquid includes deionized water, an alkali solution, and an ammonia solution. The volume of the bottom liquid is 1 / 5 - 1 / 2 of the volume of the reactor. The ammonia concentration of the bottom liquid is 2.0 - 6.0 g / L, and the pH is 11.10 - 12.30.

[0013] Further, in Step 3, the reaction temperature of the reactor is 50 - 70 °C, and the stirring speed is 100 - 170 rpm; the feeding rate of the mixed salt solution is 900 - 1200 L / h.

[0014] Further, in Step 3, an oxidant is also added to the reactor. The oxidant is air or hydrogen peroxide; when the oxidant is air, the volume of the air is 0.1 - 10% of the volume of the protective gas.

[0015] Further, in Step 3, when the first inflection point appears in the particle size of the precipitate particles, the precipitation reaction enters the first growth stage. The first inflection point refers to the minimum particle size after the precipitate particles are depolymerized from agglomeration; when the solid content of the reaction system reaches 350 - 550 g / L, the precipitation reaction enters the second growth stage; the pH of the reaction system is 11.10 - 12.30. In the first growth stage and / or the second growth stage, the pH is decreased by rapid drop, slow drop, or stepwise drop.

[0016] Further, the time for rapid pH drop is 0.5 - 1.5 h; the time for slow pH drop is 5 - 15 h; pH stepwise drop means that the pH value remains stable during the platform time and gradually decreases during the drop time. The platform time is 2 - 6 h, and the drop time is 0.5 - 1 h.

[0017] Further, in step 3, the ammonia concentration in the reaction system is 2.5-11.0 g / L; in the nucleation stage, the first growth stage, and the second growth stage, the ammonia concentrations in the reaction system are C0, C1, and C2 in sequence, C0≤C1 and C0≤C2, and the ammonia concentration is adjusted in the first growth stage and / or the second growth stage.

[0018] Further, in step 4, the target particle size is 4.0-6.0 μm, and the aging time is 2-4 h.

[0019] The present invention also provides a high-nickel precursor, which is prepared by the preparation method of the high-nickel precursor described above.

[0020] Further, the chemical formula of the high-nickel precursor is Ni x Co y Mn z (OH)2, where x + y + z = 1, and 0.8 < x < 0.96, 0.01 < y < 0.2, 0.01 < z < 0.2.

[0021] The present invention has the following beneficial effects:

[0022] The pH0 in the nucleation stage is relatively high, which is conducive to quickly generating a large number of fine and uniform crystal nuclei; the high pH value promotes the rapid reaction of metal ions with OH- ions to form hydroxide precipitates; in addition, the high pH value helps the reaction system to form uniform fine particles, with a fast crystal nucleus generation rate and good crystallinity;

[0023] In the first growth stage, when pH1 is appropriately reduced, the particle growth rate can be slowed down, promoting the uniform growth of particles, optimizing the particle morphology and particle size distribution, and obtaining precipitate particles with a more regular particle morphology, smooth surface, uniform particle size, and more complete lattice structure;

[0024] In the second growth stage, when pH2 is further reduced, the particle growth rate can be slowed down, optimizing and modifying the compactness and morphology of particles, and obtaining precipitate particles with a more compact particle morphology, smooth surface, more uniform particle size distribution, and fewer lattice defects;

[0025] Through the regulation of pH in the above three stages, a high-nickel precursor with high crystallinity, low sodium and sulfur content, and controllable BET and morphology can be prepared. Description of the Drawings

[0026] Figure 1 It is the SEM diagram of the precursor prepared in Example 1 of the present invention;

[0027] Figure 2 It is the SEM diagram of the precursor prepared in Example 2 of the present invention;

[0028] Figure 3 SEM image of the precursor prepared in Example 3 of the present invention;

[0029] Figure 4 SEM image of the precursor prepared in Example 4 of the present invention;

[0030] Figure 5 SEM image of the precursor prepared in Example 5 of the present invention;

[0031] Figure 6 SEM image of the precursor prepared in Comparative Example 1 of the present invention. Detailed implementation manners

[0032] A preparation method of a high-nickel precursor includes the following steps:

[0033] Step 1: Prepare an alkali solution, an ammonia solution, and a mixed salt solution containing nickel, cobalt, and manganese;

[0034] Step 2: Add a bottom liquid into a reaction kettle;

[0035] Step 3: Introduce a protective gas into the reaction kettle, and add the mixed salt solution, the alkali solution, and the ammonia solution into the reaction kettle to carry out a precipitation reaction to obtain precipitate particles; the precipitation reaction includes three stages, which are the nucleation stage, the first growth stage, and the second growth stage in sequence as the reaction proceeds. The pH values of the reaction systems corresponding to the three stages are pH0, pH1, and pH2 respectively, and pH0 ≤ pH1 ≤ pH2;

[0036] Step 4: Stop feeding when it is detected that the particle size D50 of the precipitate particles reaches the target particle size, and after aging, a high-nickel type precursor is prepared through post-treatment.

[0037] By controlling the pH value of the reaction system during the precipitation reaction of the present invention, the pH0 in the nucleation stage is relatively high, which is beneficial to quickly generate a large number of fine and uniform crystal nuclei; the high pH value promotes the rapid reaction of metal ions (such as Ni 2 +, Co2+, Mn2+) with OH- ions to form hydroxide precipitates; in addition, the high pH value helps the reaction system to form uniform fine particles, the crystal nucleus generation rate is fast, and the crystallinity is good; in the first growth stage, pH1 is appropriately reduced, which can slow down the particle growth rate, promote the uniform growth of particles, optimize the morphology and particle size distribution of particles, and obtain precipitate particles with more regular particle morphology, smooth surface, uniform particle size, and more complete lattice structure; in the second growth stage, pH2 is further reduced, which can slow down the particle growth rate, optimize and modify the compactness and morphology of particles, and obtain precipitate particles with more compact particle morphology, smooth surface, more uniform particle size distribution, and fewer lattice defects; through the regulation of the pH in the above three stages, a high-nickel precursor with high crystallinity, low sodium and sulfur content, controllable BET and morphology can be prepared.

[0038] Further, in Step 1, soluble salts of nickel, cobalt, and manganese are used as raw materials and are formulated into a mixed salt solution with pure water in a certain proportion, and an alkali solution (NaOH solution) and an ammonia solution with certain concentrations are prepared according to the proportion; the molar concentration of the mixed salt solution is 1.0 - 3.0 mol / L, the molar concentration of the alkali solution is 4.0 - 11.0 mol / L, and the mass concentration of the ammonia solution is 8.0 - 12%.

[0039] Further, in Step 2, the bottom liquid is the start-up water, including deionized water, an alkali solution, and an ammonia solution. The volume of the bottom liquid is 1 / 5 - 1 / 2 of the volume of the reaction kettle. The ammonia concentration in the bottom liquid is 2.0 - 6.0 g / L, the pH of the bottom liquid is 11.10 - 12.30, and the alkali solution and ammonia solution in the bottom liquid can be the alkali solution and ammonia solution prepared in the above Step 1.

[0040] Further, in Step 3:

[0041] The reaction temperature of the reaction kettle is 50 - 70 °C, and the stirring speed is 100 - 170 rpm; the feeding rate of the mixed salt solution (hereinafter represented by the NCM flow rate) is 900 - 1200 L / h; among them, in the above Step 2, the bottom liquid can be stirred at a stirring speed of 100 - 170 rpm, and when feeding materials into the reaction kettle, it can also be continuously stirred.

[0042] An oxidant is also added to the reaction kettle. The oxidant is air or hydrogen peroxide, but not limited to this; when the oxidant is air, the volume of the air introduced is 0.1 - 10% of the volume of the protective gas (indicating that the oxidation degree of the air is 0.1 - 10%), and the protective gas can be nitrogen. Among them, air can be introduced in the nucleation stage, the first growth stage, and the second growth stage. Introducing a small amount of oxygen in the nucleation stage can promote the oxidation of metal ions, increase the supersaturation of the reaction system, be conducive to quickly generating a large number of fine and uniform crystal nuclei, and can also optimize the surface state of the crystal nuclei, providing a good foundation for the subsequent growth stage; introducing a small amount of oxygen in the first growth stage can adjust the growth rate of the particles and promote the uniform growth of the particles; introducing a small amount of oxygen in the second growth stage can further optimize the compactness and morphology of the particles, adjust the surface state of the particles, and increase the tap density (TD) and crystallinity.

[0043] In this embodiment, when the particle size of the precipitation particles shows the first inflection point, the precipitation reaction enters the first growth stage. The first inflection point is the smallest particle size of the precipitation particles after the precipitation particles change from agglomeration to depolymerization; when the solid content of the reaction system is 350 - 550 g / L, the precipitation reaction enters the second growth stage; the pH of the reaction system is 11.10 - 12.30. In the first growth stage and / or the second growth stage, the pH is adjusted downward rapidly, slowly, or stepwise.

[0044] Specifically, the preparation method of the high-nickel precursor includes three key growth stages. First, in the first stage, through the nucleation process, grains are formed under high supersaturation and then agglomerated into spherical-like shapes. As the coprecipitation reaction proceeds, the spherical-like shapes will depolymerize, and the overall particle size will decrease, with the first inflection point appearing in the particle size trend. Subsequently, the reaction enters the second stage. By adjusting the pH, ammonia concentration, and oxidant, the primary particles begin to grow towards the target morphology, namely spindle-shaped, plate-like strip-shaped, needle-like, and the primary particle sizes are staggered, etc. When the solid content is 350 - 550 g / L, the reaction enters the third stage. This stage mainly addresses the impact of high solid content on the morphology and indicators under high input. By adjusting the pH, ammonia concentration, and oxidant, the primary particles continue to grow towards the target morphology, namely spindle-shaped, plate-like strip-shaped, needle-like, and the primary particle sizes are staggered, etc. At the same time, by adjusting the key parameters, the expected indicators can be achieved, including specific surface area, tapped density, impurity level, etc.

[0045] Among them, the rapid pH drop time is 0.5 - 1.5 h; the slow pH drop time is 5 - 15 h; the stepped pH drop means that the pH value remains stable within the platform time and gradually decreases within the drop time. The platform time is 2 - 6 h, and the drop time is 0.5 - 1 h. The platform time refers to the time period when the pH value remains stable, and the drop time refers to the time period when the pH value gradually decreases.

[0046] Specifically, the node for starting to adjust the pH in the first growth stage is determined according to the first inflection point of the particle size detection data trend. The pH in this stage ≤ the pH in the nucleation stage. The purpose is to allow the particles generated by nucleation to grow uniformly by agglomeration. The adjustment methods from the pH in the nucleation stage to the pH in the first growth stage include but are not limited to rapid drop, slow drop, and stepped drop. The pH in the second growth stage is adjusted according to the solid content of 350 g / L - 550 g / L. Generally, the pH in the second growth stage ≤ the pH in the first growth stage. The adjustment methods from the pH in the first growth stage to the pH in the second growth stage include but are not limited to rapid drop, slow drop, and stepped drop.

[0047] In this embodiment, the ammonia concentration in the reaction system is 2.5 - 11.0 g / L. In the nucleation stage, the first growth stage, and the second growth stage, the ammonia concentrations in the reaction system are C0, C1, and C2 in sequence, C0 ≤ C1 and C0 ≤ C2, and the ammonia concentration is adjusted in the first growth stage and / or the second growth stage. The adjustment node of the ammonia concentration corresponds to the adjustment node of the pH, aiming to reasonably match the pH and control the precipitation rate and supersaturation.

[0048] Specifically, in the nucleation stage, at low ammonia concentration, the complexation of metal ions is weak, and the concentration of free metal ions is high, which is conducive to the rapid formation of a large number of fine and uniform crystal nuclei, and the supersaturation of the reaction system is high, promoting the rapid formation of crystal nuclei; in the first growth stage, C0 ≤ C1, increasing the ammonia concentration can enhance the complexation of metal ions, reduce the concentration of free metal ions, thereby slowing down the particle growth rate and promoting the uniform growth of particles; in the second growth stage, C0 ≤ C2, appropriately increasing the ammonia concentration can further slow down the particle growth rate, optimize the compactness and morphology of particles. Compared with C1 in the first growth stage, C2 can increase, decrease or remain unchanged. Thus, the appearance of the precipitate particles can be well modified to obtain the desired finished product.

[0049] Further, in step 4, the target particle size is 4.0 - 6.0 μm, and the aging time is 2 - 4 h. Among them, the post-treatment includes washing, drying, sieving, iron removal, and packaging.

[0050] The present invention also provides a high-nickel precursor, which is prepared by the preparation method of the high-nickel precursor as described above.

[0051] Further, the chemical formula of the high-nickel precursor is NixCoyMnz(OH)2, where x + y + z = 1, and 0.8 < x < 0.96, 0.01 < y < 0.2, 0.01 < z < 0.2.

[0052] The present invention can optimize the morphology, particle size distribution, crystallinity, and physical and chemical properties of the high-nickel precursor by regulating the pH values (pH0, pH1, pH2) and ammonia concentrations (C0, C1, C2) of the reaction system in stages, and then combining with the regulation of other process parameters (such as reaction temperature, stirring rate, NCM flow rate, oxidation conditions); these factors affect and restrict the sphericity, primary particle morphology, specific surface area (BET), tap density, and crystallinity of the precursor. By controlling the process parameters in the coprecipitation process, the present invention can obtain a ternary precursor with optimized specific surface area, tap density, and density.

[0053] The following further describes the present invention in detail with reference to test examples and specific embodiments. However, this should not be understood as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments. All technologies implemented based on the content of the present invention belong to the scope of the present invention.

[0054] Examples

[0055] Example 1:

[0056] This embodiment provides a high-nickel precursor with controllable morphology and specific surface area and high productivity, and a preparation method thereof. The molar ratio of nickel, cobalt, and manganese elements in the metal salt solution is x / y / z, (x + y + z = 1, 0.8 < x < 0.96, 0.01 < y < 0.3, 0.01 < z < 0.2), and D50 = 4.0 - 5.0 μm. The preparation process is as follows:

[0057] S1. Select soluble salts of nickel, cobalt, and manganese as raw materials and prepare a mixed salt solution with pure water. The total concentration of nickel metal ions is 2.3 mol / L;

[0058] S2. Prepare an 8.0 mol / L alkali solution and a 9% ammonia water;

[0059] S3. Open the jacket inlet and return water of the reaction kettle, add pure water to the reaction kettle to 1 / 3 of the reaction kettle volume, start the stirring of the reaction kettle at 100 - 150 rpm, heat up to 60 ± 0.5 °C, then add the alkali solution and ammonia water prepared in S2, and adjust the pH value of the bottom liquid to 11.90 - 12.05, and the ammonia concentration is 4 ± 0.3 g / L;

[0060] S4. Under nitrogen protection, add the mixed salt solution prepared in S1, the alkali solution and ammonia water prepared in S2 into the reaction kettle simultaneously in three paths. The nucleation time in the first-stage nucleation stage is 1 h, the degree of air oxidation is 2% (referring to the volume content of air relative to the protective gas nitrogen is 2%), the feeding rate of the mixed salt solution is 900 - 1000 L / h, the pH is controlled at 11.90 - 12.05 (pH0), and the ammonia concentration is controlled at 4 ± 0.3 g / L (C0);

[0061] S5. When the first inflection point appears in the particle size growth trend, enter the first growth stage. The pH rapid drop in 1 h is controlled at 11.80 - 12.00 (pH1) / 45 °C, the ammonia concentration gradually rises and is controlled at 8.0 - 9.0 g / L (C1), and the feeding rate of ammonia water is regulated according to the ammonia concentration;

[0062] S6. When the solid content reaches 450 - 500 g / L, enter the second growth stage. The pH is controlled at 11.80 - 12.00 (pH2) / 45 °C, and the ammonia concentration is controlled at 8.0 - 9.0 g / L (C2);

[0063] S7. When it is detected that D50 reaches 4 μm, stop feeding, and age in the reaction kettle for 2 h;

[0064] S8. Wash, dry, sieve, and demagnetize the stopped slurry in S7 to obtain the required precursor product.

[0065] Example 2:

[0066] This embodiment provides a high-nickel precursor with controllable morphology and specific surface area and high productivity, and a preparation method thereof. The specific operation steps are different from those of Embodiment 1. In the second growth stage, an oxidant, i.e., air, is supplemented, and the air oxidation degree is 2%.

[0067] Embodiment 3:

[0068] This embodiment provides a high-nickel precursor with controllable morphology and specific surface area and high productivity, and a preparation method thereof. The molar ratio of nickel, cobalt, and manganese elements in the metal salt solution is x / y / z, (x + y + z = 1, 0.8 < x < 0.96, 0.01 < y < 0.3, 0.01 < z < 0.2), and D50 = 4.0 - 5.0 μm. The preparation process is as follows:

[0069] S1. Select soluble salts of nickel, cobalt, and manganese as raw materials and prepare a mixed salt solution with pure water. The total metal ion concentration is 2.3 mol / L;

[0070] S2. Prepare an 8.0 mol / L alkali solution and a 9% ammonia water;

[0071] S3. Open the jacket inlet and return water of the reaction kettle, add pure water to the reaction kettle to 1 / 3 of the reaction kettle volume, start the stirring of the reaction kettle at 100 - 150 rpm, heat up to 60 ± 0.5 °C, then add the liquid alkali and ammonia water prepared in S2, and adjust the pH value of the bottom liquid to 11.90 - 12.05 / 45 °C, and the ammonia concentration is 4 ± 0.3 g / L;

[0072] S4. Under nitrogen protection, add the mixed salt solution prepared in S1, the liquid alkali and ammonia water prepared in S2 into the reaction kettle simultaneously in three streams. The nucleation time in the first-stage nucleation stage is 1.5 h, the air oxidation degree is 4%, the feeding rate of the mixed salt solution is 900 - 1000 L / h, the pH is controlled at 11.90 - 12.05 (pH0), and the ammonia concentration is controlled at 4 ± 0.3 g / L (C0);

[0073] S5. When the first inflection point appears in the particle size growth trend, enter the first growth stage. The pH slowly drops for 5 h and is controlled at 11.65 - 11.85 (pH1), the ammonia concentration gradually rises and is controlled at 7.0 - 8.0 g / L (C1), and the feeding rate of ammonia water is adjusted according to the ammonia concentration;

[0074] S6. When the solid content reaches 420 - 450 g / L, enter the second growth stage. The pH rapidly drops for 1 h and is controlled at 11.50 - 11.60 (pH2), and the ammonia concentration is controlled at 7.0 - 8.0 g / L (C2);

[0075] S7. When it is detected that D50 reaches 4 μm, stop feeding, and age in the reaction kettle for 2 h;

[0076] In S8, the stopped slurry in S7 is washed, dried, sieved, and demagnetized to obtain the required precursor product.

[0077] Example 4:

[0078] This example provides a high-nickel precursor with controllable morphology and specific surface area and high productivity, and a preparation method thereof. The molar ratio of nickel, cobalt, and manganese elements in the metal salt solution is x / y / z, (x + y + z = 1, 0.8 < x < 0.96, 0.01 < y < 0.3, 0.01 < z < 0.2), and D50 = 4.0 - 5.0 μm. The preparation process is as follows:

[0079] S1, Select soluble salts of nickel, cobalt, and manganese as raw materials and mix them with pure water to prepare a mixed salt solution, with the total metal ion concentration being 2.3 mol / L;

[0080] S2, Prepare an 8.0 mol / L alkali solution and a 9% ammonia water;

[0081] S3, Open the jacket inlet and return water of the reaction kettle, add pure water to the reaction kettle to 1 / 3 of the reaction kettle volume, start stirring the reaction kettle at 100 - 150 rpm, heat up to 60 ± 0.5 °C, then add the liquid alkali and ammonia water prepared in S2, and adjust the pH value of the bottom liquid to 11.90 - 12.05 / 45 °C, with the ammonia concentration being 4 ± 0.3 g / L;

[0082] S4, Under nitrogen protection, add the mixed salt solution prepared in S1, the liquid alkali and ammonia water prepared in S2 into the reaction kettle simultaneously in three streams. The nucleation time in the first-stage nucleation stage is 2.5 h, the air oxidation degree is 5%, the feeding rate of the mixed salt solution is 900 - 1000 L / h, the pH is controlled at 11.90 - 12.05 (pH0), and the ammonia concentration is controlled at 4 ± 0.3 g / L (C0);

[0083] S5, When the first inflection point appears in the particle size growth trend, enter the first growth stage. The pH rapid drop in 1 h is controlled at 11.80 - 11.95 (pH1), the ammonia concentration gradually rises and is controlled at 7.0 - 8.0 g / L (C1), and at the same time, an oxidant, i.e., air, is supplemented, with the oxidation degree being 2%;

[0084] S6, When the solid content reaches 400 - 450 g / L, enter the second growth stage. The pH slow drop in 5 h is controlled at 11.50 - 11.60 (pH2), the ammonia concentration is controlled at 7.0 - 8.0 g / L (C2), and at the same time, the oxidation is adjusted, with the oxidation degree being 3%;

[0085] S7, When it is detected that D50 reaches 4.0 μm, stop feeding, and age in the reaction kettle for 2 h;

[0086] In S8, the slurry for shutdown in S7 is washed, dried, sieved, and demagnetized to obtain the required precursor product.

[0087] Example 5:

[0088] This example provides a high-nickel precursor with controllable morphology and specific surface area and a high production capacity, and a preparation method thereof. The molar ratio of nickel, cobalt, and manganese elements in the metal salt solution is x / y / z, (x + y + z = 1, 0.8 < x < 0.96, 0.01 < y < 0.3, 0.01 < z < 0.2), and D50 = 4.0 - 5.0 μm. The preparation process is as follows:

[0089] S1, Select soluble salts of nickel, cobalt, and manganese as raw materials and prepare a mixed salt solution with pure water. The total metal ion concentration is 2.3 mol / L;

[0090] S2, Prepare an 8.0 mol / L alkali solution and a 9% ammonia water;

[0091] S3, Open the jacket inlet and return water of the reactor, add pure water to the reactor to 1 / 3 of the reactor volume, start the reactor stirrer at 100 - 150 rpm, heat up to 60 ± 0.5 °C, then add the liquid alkali and ammonia water prepared in S2, and adjust the pH value of the bottom liquid to 11.90 - 12.05 / 45 °C, and the ammonia concentration is 4 ± 0.3 g / L;

[0092] S4, Under nitrogen protection, add the mixed salt solution prepared in S1, the liquid alkali and ammonia water prepared in S2 into the reactor simultaneously in three ways. The nucleation time in the first-stage nucleation stage is 1 h, the air oxidation degree is 5%, the feeding rate of the mixed salt solution is 900 - 1000 L / h, the pH is controlled at 11.90 - 12.05 (pH0), and the ammonia concentration is controlled at 4 ± 0.3 g / L (C0);

[0093] S5, When the first inflection point appears in the particle size growth trend, enter the first growth stage. The pH slowly drops for 5 h and is controlled at 11.75 - 11.85 (pH1), the ammonia concentration gradually rises and is controlled at 6.0 - 7.0 g / L (C1), and at the same time, an oxidant, i.e., air, is supplemented, and the oxidation degree is 2%;

[0094] S6, When the solid content reaches 480 - 520 g / L, enter the second growth stage. The pH slowly drops for 6 h and is controlled at 11.30 - 11.40 (pH2), the ammonia concentration is controlled at 4.0 - 5.0 g / L (C2), and at the same time, the oxidation is adjusted, and the oxidation degree is 4%;

[0095] S7, When it is detected that D50 reaches 4.0 μm, stop feeding, and age in the reactor for 2 h;

[0096] S8. The slurry for shutdown in S7 is washed, dried, sieved, and demagnetized to obtain the required precursor product.

[0097] Comparative Example

[0098] Comparative Example 1:

[0099] This comparative example provides a method for preparing a high-nickel precursor by the original process. The molar ratio of nickel, cobalt, and manganese elements in the metal salt solution is x / y / z, (x + y + z = 1, 0.8 < x < 0.96, 0.01 < y < 0.3, 0.01 < z < 0.2), and D50 = 4.0 - 5.0 μm. The preparation process is as follows:

[0100] S1. Select soluble salts of nickel, cobalt, and manganese as raw materials and prepare a mixed salt solution with pure water. The total concentration of metal ions is 2.3 mol / L.

[0101] S2. Prepare an 8.0 mol / L alkali solution and a 9% ammonia water.

[0102] S3. Open the inlet and return water of the jacket of the reaction kettle, add pure water to the reaction kettle to 1 / 3 of the volume of the reaction kettle, start the stirring of the reaction kettle at 100 - 150 rpm, heat up to 60 ± 0.5 °C, then add the alkali solution and ammonia water prepared in S2, and adjust the pH value of the bottom liquid to 11.90 - 12.05 / 45 °C, and the ammonia concentration is 4 ± 0.3 g / L.

[0103] S4. Under the protection of nitrogen, add the mixed salt solution prepared in S1, the alkali solution and ammonia water prepared in S2 into the reaction kettle simultaneously in three ways. The feeding rate of the salt solution is 900 - 1000 L / h. After nucleation, keep the pH unchanged, control the pH at 11.90 - 12.00 / 45 °C, the ammonia concentration gradually increases and is controlled at 7.0 - 8.0 g / L, and the feeding rate of ammonia water is adjusted according to the ammonia concentration.

[0104] S5. When it is detected that D50 reaches 4.0 μm, stop feeding, and age in the reaction kettle for 2 h.

[0105] S6. The slurry for shutdown in S5 is washed, dried, sieved, and demagnetized to obtain the required precursor product.

[0106] Comparative Example 2:

[0107] This comparative example provides a high-nickel precursor with high cost and its preparation method. The molar ratio of nickel, cobalt, and manganese elements in the metal salt solution is x / y / z, (x + y + z = 1, 0.8 < x < 0.96, 0.01 < y < 0.3, 0.01 < z < 0.2), and D50 = 4.0 - 5.0 μm. The preparation process is as follows:

[0108] S1. Select nickel, cobalt, and manganese soluble salts as raw materials and prepare a mixed salt solution with pure water. The total concentration of metal ions is 2.3 mol / L.

[0109] S2. Prepare an 8.0 mol / L lye solution and a 9% ammonia water solution.

[0110] S3. Open the jacket water inlet and return water of the reaction kettle, add pure water to the reaction kettle to 1 / 3 of its volume, start the stirring of the reaction kettle at 100 - 150 rpm, heat up to 60 ± 0.5 °C, then add the lye solution and ammonia water prepared in S2, and adjust the pH value of the bottom liquid to 11.95 - 12.05 / 45 °C, with the ammonia concentration being 3 ± 0.3 g / L.

[0111] S4. Under nitrogen protection, simultaneously add the mixed salt solution prepared in S1, the lye solution, and the ammonia water prepared in S2 into the reaction kettle in three streams. The feeding rate of the salt solution is 900 - 1000 L / h, the nucleation time is 20 min. After nucleation, the pH value is rapidly decreased to 11.10 - 11.25 / 45 °C within 1.5 h, and then stably controlled within this range. The ammonia concentration is stably controlled at 3.0 - 4.5 g / L, and the feeding rate of the ammonia water is adjusted according to the ammonia concentration.

[0112] S5. When it is detected that D50 reaches 4.0 μm, stop feeding, and age the slurry in the reaction kettle for 2 h.

[0113] S6. Wash, dry, screen, and demagnetize the stopped slurry in S5 to obtain the required precursor product.

[0114] Performance Test and Conclusion Analysis

[0115] By measuring the performance of the products obtained from the above-mentioned examples and comparative examples, the results shown in Table 1 are obtained.

[0116] Table 1 Performance Data of High-Nickel Precursors in Each Example and Comparative Example

[0117]

[0118] From Table 1, Figures 1 to 6 (SEM Morphology), it can be found that:

[0119] (1) Morphology Controllability: Through the coordinated action of pH, ammonia concentration, and oxidation, the controllability of the high-nickel precursor morphology is successfully achieved, and various morphologies such as spindle-shaped (such as Figure 1 and Figure 4 ), plate-like strip-shaped (such as Figure 2 ), needle-like (such as Figure 5 ), and primary particle interlaced type (such as Figure 3 ) are obtained; the regulation of these morphologies significantly optimizes the specific surface area (BET) and tap density (TD) of the precursor.

[0120] (2) Low impurity levels: In Examples 1 - 5, the impurity contents of sodium (Na) and sulfur (S) are significantly lower than those in Comparative Example 1 and Comparative Example 2, indicating that the method of the present invention has significant advantages in reducing impurity levels, thereby reducing the subsequent washing cost.

[0121] (3) Process parameter optimization: By regulating the pH values (pH0, pH1, pH2) and ammonia concentrations (C0, C1, C2) in stages, and combining with the addition of oxidants, fine control over particle nucleation, growth, and densification is achieved, significantly improving the crystallinity and morphological uniformity of the precursor.

[0122] (4) High productivity and low cost: The input of high - throughput NCM significantly improves production efficiency, and at the same time reduces the production cost per ton by optimizing process parameters, showing significant potential for industrial application.

[0123] (5) Outstanding advantages of comparative experiments: Compared with Comparative Example 1 (original process) and Comparative Example 2 (high - cost process), the present invention shows significant advantages in terms of morphology controllability, impurity levels, tap density, and specific surface area, further verifying the innovation and practicality of the present invention.

[0124] In summary, by regulating the pH value, ammonia concentration, and oxidation conditions of the reaction system in stages, the present invention successfully prepares a high - nickel precursor with high crystallinity, low sodium and sulfur content, controllable BET and morphology, providing important support for improving the performance of lithium - battery cathode materials and having broad application prospects.

[0125] The above - mentioned are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

1. A preparation method of a high-nickel precursor, characterized in that, It includes the following steps: Step 1: Configure an alkali solution, an ammonia solution, and a mixed salt solution containing nickel, cobalt, and manganese; Step 2: Add a bottom liquid into the reaction kettle; Step 3: Introduce a protective gas into the reaction kettle, and add the mixed salt solution, the alkali solution, and the ammonia solution into the reaction kettle to carry out a precipitation reaction to obtain precipitate particles; the precipitation reaction includes three stages, which are the nucleation stage, the first growth stage, and the second growth stage in sequence as the reaction proceeds. The pH values of the reaction systems corresponding to the three stages are pH0, pH1, and pH2 respectively, and pH0 ≤ pH1 ≤ pH2; Step 4: Stop feeding when it is detected that the particle size D50 of the precipitate particles reaches the target particle size, and after aging, a high-nickel type precursor is prepared through post-treatment.

2. The preparation method of the high-nickel precursor according to claim 1, wherein, In Step 1, the molar concentration of the mixed salt solution is 1.0 - 3.0 mol / L, the molar concentration of the alkali solution is 4.0 - 11.0 mol / L, and the mass concentration of the ammonia solution is 8.0 - 12%.

3. The preparation method of the high-nickel precursor according to claim 1, characterized in that, In Step 2, the bottom liquid includes deionized water, an alkali solution, and an ammonia solution. The volume of the bottom liquid is 1 / 5 - 1 / 2 of the volume of the reaction kettle. The ammonia concentration of the bottom liquid is 2.0 - 6.0 g / L, and the pH is 11.10 - 12.

30.

4. The preparation method of the high-nickel precursor according to claim 1, characterized in that, In Step 3, the reaction temperature of the reaction kettle is 50 - 70 °C, and the stirring speed is 100 - 170 rpm; the feeding rate of the mixed salt solution is 900 - 1200 L / h.

5. The preparation method of the high-nickel precursor according to claim 1, characterized in that, In Step 3, an oxidant is also added into the reaction kettle. The oxidant is air or hydrogen peroxide; when the oxidant is air, the volume of the introduced air is 0.1 - 10% of the volume of the protective gas.

6. The preparation method of the high-nickel precursor according to claim 1, characterized in that, In Step 3, when the particle size of the precipitate particles shows the first inflection point, the precipitation reaction enters the first growth stage. The first inflection point refers to the minimum particle size after the precipitate particles are aggregated and then depolymerized; when the solid content of the reaction system reaches 350 - 550 g / L, the precipitation reaction enters the second growth stage; the pH of the reaction system is 11.10 - 12.

30. In the first growth stage and / or the second growth stage, the pH is adjusted to decrease rapidly, slowly, or stepwise.

7. The preparation method of the high-nickel precursor according to claim 6, characterized in that, The time for rapid pH decrease is 0.5 - 1.5 h; the time for slow pH decrease is 5 - 15 h; pH stepwise decrease means that the pH value remains stable during the platform time and gradually decreases during the decreasing time. The platform time is 2 - 6 h, and the decreasing time is 0.5 - 1 h.

8. The preparation method of the high-nickel precursor according to claim 1, characterized in that, In Step 3, the ammonia concentration of the reaction system is 2.5 - 11.0 g / L; in the nucleation stage, the first growth stage, and the second growth stage, the ammonia concentrations of the reaction system are C0, C1, and C2 respectively, C0 ≤ C1 and C0 ≤ C2, and the ammonia concentration is adjusted in the first growth stage and / or the second growth stage.

9. The preparation method of the high-nickel precursor according to claim 1, wherein, In Step 4, the target particle size is 4.0 - 6.0 μm, and the aging time is 2 - 4 h.

10. A high-nickel precursor, characterized in that, It is prepared by the preparation method of the high-nickel precursor according to any one of claims 1 - 9.

11. The high-nickel precursor according to claim 10, wherein The chemical formula of the high-nickel precursor is Ni x Co y Mn z (OH)2, where x + y + z = 1, and 0.8 < x < 0.96, 0.01 < y < 0.2, 0.01 < z < 0.2.

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