A method for preparing a ternary positive electrode precursor by using a nickel-cobalt-manganese-containing ammonia leaching solution to prepare ammonia

Abstract

This invention provides a method for preparing a ternary cathode precursor using a nickel-cobalt-manganese ammonia leaching solution with ammonia stripping. The method includes the following steps: providing a nickel-cobalt-manganese ammonia leaching solution; injecting the nickel-cobalt-manganese ammonia leaching solution and liquid alkali into the base solution in a parallel flow, and reacting under open ammonia stripping conditions to obtain a reaction solution; adjusting the pH of the reaction solution and then aging it to obtain an agglomeration precursor solution; and performing hydrothermal crystallization treatment on the agglomeration precursor solution to obtain the ternary cathode precursor through solid-liquid separation. This invention directly uses a nickel-cobalt-manganese ammonia leaching solution as raw material, achieving in-situ dissociation and co-precipitation of metal complexes through open ammonia stripping. The distilled ammonia gas can be recovered and recycled for use in the leaching process. While obtaining the cathode precursor, it achieves closed-loop utilization of ammonia water. After aging, hydrothermal crystallization treatment significantly improves the crystallization degree of the precursor, optimizes particle morphology and density, and thus obtains a high-quality ternary cathode precursor with complete crystals, few internal defects, and high density.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology and relates to a method for preparing ternary cathode precursors using a nickel-cobalt-manganese-containing ammonia immersion solution with ammonia vaporization. Background Technology

[0002] Lithium-ion batteries, with their advantages of high energy density, long cycle life, and environmental friendliness, have been widely used in portable electronic devices, electric vehicles, and large-scale energy storage systems. Among them, NCM ternary cathode materials have become the mainstream technology for lithium-ion battery cathode materials due to their combination of the high energy density of nickel, the excellent electrochemical performance of cobalt, and the cost-effectiveness and structural stability of manganese / aluminum.

[0003] The electrochemical performance of ternary cathode materials is largely inherited from their precursor materials. The chemical composition, crystal structure, particle morphology, particle size distribution, and density of NCM ternary precursors directly determine the specific capacity, rate performance, and cycle stability of the final cathode material. Therefore, the controllable preparation of high-performance ternary precursors is a key prerequisite for achieving high-quality ternary cathode materials.

[0004] Currently, the most widely used method for synthesizing ternary precursors in industrial production is the coprecipitation method. This method uses soluble salts of nickel, cobalt, and manganese (usually sulfates) as raw materials, sodium hydroxide as a precipitant, and ammonia as a complexing agent. In a reaction vessel, by controlling parameters such as pH, temperature, and stirring speed, metal ions are co-precipitated as hydroxides, ultimately yielding spherical or near-spherical ternary precursor particles. However, the traditional coprecipitation method uses high-purity nickel sulfate, cobalt sulfate, and manganese sulfate as raw materials, resulting in high raw material costs. Furthermore, the large consumption of precipitants and complexing agents increases material costs. Simultaneously, this process generates a large amount of wastewater containing sodium sulfate, increasing the burden on environmental treatment and wasting valuable resources.

[0005] Ammonia leaching technology utilizes the selective complexing ability of the ammonia-ammonium salt system to efficiently leach valuable metals such as nickel and cobalt from low-grade nickel-cobalt ore, laterite nickel ore, or waste ternary lithium battery cathode materials, yielding a leachate containing nickel-cobalt-ammonia complexes. However, existing technologies often involve first subjecting the nickel-cobalt-manganese-containing ammonia leaching solution to ammonia stripping to break down the metal-ammonia complexes, causing the metal ions to precipitate out as hydroxides or carbonates. These precipitates are then redissolved to prepare a sulfate solution, which is then used in a conventional co-precipitation process to prepare the precursor. This method is cumbersome and carries the risk of metal loss and impurity introduction. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing ternary cathode precursors using ammonia leaching solution containing nickel, cobalt, and manganese through ammonia evaporation. This invention directly uses the nickel, cobalt, and manganese-containing ammonia leaching solution as raw material, achieving in-situ dissociation and co-precipitation of metal complexes through open ammonia evaporation. The distilled ammonia gas can be recycled for use in the leaching process. Simultaneously, the ammonia water is utilized in a closed-loop manner while obtaining the cathode precursor. After aging, hydrothermal crystallization treatment significantly improves the crystallization degree of the precursor, optimizes particle morphology and density, and thus yields a high-quality ternary cathode precursor with complete crystals, few internal defects, and high density.

[0007] To achieve this objective, the present invention employs the following technical solution: This invention provides a method for preparing a ternary cathode precursor using a nickel-cobalt-manganese-containing ammonia leaching solution with ammonia vapor extraction, the method comprising the following steps: Provide ammonia leaching solution containing nickel, cobalt, and manganese; A nickel-cobalt-manganese-containing ammonia leaching solution and liquid alkali were injected into the bottom solution in a parallel flow, and the reaction was carried out under open ammonia stripping conditions to obtain a reaction solution; After adjusting the pH of the reaction solution, it was aged to obtain an agglomeration precursor solution. The agglomeration precursor solution was subjected to hydrothermal crystallization treatment, and the solid-liquid separation was performed to obtain the ternary cathode precursor.

[0008] This invention utilizes a nickel-cobalt-manganese ammonia leaching solution under open ammonia stripping conditions to prepare a precursor. In this solution, nickel, cobalt, and manganese ions exist as complex ions. Under open ammonia stripping conditions, ammonia continuously volatilizes and escapes, the complexes dissociate, and the metal ions undergo in-situ hydrolysis and co-precipitation to generate a hydroxide precursor. The evaporated ammonia is absorbed, condensed, and then returned to the leaching section to prepare the leaching agent, achieving a closed-loop ammonia cycle. No other impurities are introduced during this process. The pH of the auxiliary liquid, adjusted by alkali, can be removed to within the standard range during subsequent product washing and is recyclable. After obtaining the reaction solution, the agglomerated precursor is aged and then subjected to hydrothermal crystallization under suitable conditions. Through recrystallization and structural reorganization, the amorphous / weakly crystalline agglomerated precursor is transformed into a hydroxide precursor with complete crystals, few internal defects, and high density.

[0009] Preferably, the mass concentration of nickel ions in the nickel-cobalt-manganese ammonia leaching solution is 30 g / L to 80 g / L, for example: 30 g / L, 50 g / L, 60 g / L, 70 g / L or 80 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0010] Preferably, the mass concentration of cobalt ions in the nickel-cobalt-manganese ammonia leaching solution is 1 g / L to 2 g / L, for example: 1 g / L, 1.2 g / L, 1.5 g / L, 1.8 g / L or 2 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0011] Preferably, the mass concentration of manganese ions in the nickel-cobalt-manganese ammonia leaching solution is 1 g / L to 5 g / L, for example: 1 g / L, 2 g / L, 3 g / L, 4 g / L or 5 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0012] Preferably, the mass concentration of sodium ions in the nickel-cobalt-manganese ammonia leaching solution is 1 g / L to 8 g / L, for example: 1 g / L, 2 g / L, 4 g / L, 6 g / L or 8 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] Preferably, the mass concentration of sulfate ions in the nickel-cobalt-manganese ammonia leaching solution is 150 g / L to 300 g / L, for example: 150 g / L, 180 g / L, 200 g / L, 250 g / L or 300 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] Preferably, the mass concentration of ammonium ions in the nickel-cobalt-manganese ammonia leaching solution is 100 g / L to 150 g / L, for example: 100 g / L, 110 g / L, 130 g / L, 140 g / L or 150 g / L, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the pH of the nickel-cobalt-manganese ammonia leaching solution is 8 to 10, for example: 8, 8.5, 9, 9.5 or 10, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] Preferably, the mass percentage concentration of the liquid alkali is 20% to 30%, for example: 20%, 22%, 25%, 28% or 30%, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] Preferably, the pH of the base solution is 10 to 11, for example: 10, 10.2, 10.5, 10.8 or 11, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] Preferably, the flow rate of the nickel-cobalt-manganese-containing ammonia leaching solution is 1.8 mL / min to 2.2 mL / min, for example: 1.8 mL / min, 1.9 mL / min, 2 mL / min, 2.1 mL / min or 2.2 mL / min, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] Preferably, the reaction temperature is 50℃~60℃, for example: 50℃, 52℃, 55℃, 58℃ or 60℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the pH of the reaction is 10 to 11, for example: 10, 10.2, 10.5, 10.8 or 11, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the reaction time is 20h to 25h, for example: 20h, 21h, 22h, 24h or 25h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, the pH of the adjusted reaction solution is 10~11.5, for example: 10, 10.2, 10.5, 11 or 11.5, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, the aging treatment temperature is 50℃~60℃, for example: 50℃, 52℃, 55℃, 58℃ or 60℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the aging process takes place for 10 to 15 hours, for example, 10 hours, 11 hours, 12 hours, 14 hours, or 15 hours. It is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0025] Preferably, the temperature of the hydrothermal crystallization treatment is 100℃~180℃, for example: 100℃, 120℃, 150℃, 160℃ or 180℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Preferably, the hydrothermal crystallization treatment time is 2h to 32h, for example: 2h, 8h, 15h, 20h or 32h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the ternary cathode precursor obtained after the hydrothermal crystallization treatment is washed.

[0028] Preferably, the washing process includes water washing and / or alkaline washing.

[0029] Preferably, the solid-liquid mass ratio of the washing process is 1:(2~4), for example: 1:2, 1:2.5, 1:3, 1:3.5 or 1:4, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] Preferably, the ternary cathode precursor includes primary grains and secondary particles formed by the stacking of primary grains.

[0031] Preferably, the morphology of the primary grains includes lamellar and / or slatted shapes.

[0032] Preferably, the thickness of the primary grain is 50nm~300nm, for example: 50nm, 80nm, 100nm, 200nm or 300nm, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the specific surface area (BET) of the ternary cathode precursor is 15 m². 2 / g~40m 2 / g, for example: 15m 2 / g、20m 2 / g、25m 2 / g、30m 2 / g or 40m 2 / g, etc., are not limited to the listed values; other unlisted values ​​within this range also apply.

[0034] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0035] Compared with the prior art, the present invention has the following beneficial effects: (1) The method for preparing ternary cathode precursors by evaporating ammonia using nickel-cobalt-manganese ammonia leaching solution provided by the present invention directly uses nickel-cobalt-manganese ammonia leaching solution as raw material to prepare precursors by evaporating ammonia in situ, eliminating intermediate steps such as impurity removal, concentration, salt conversion, and redissolution of leaching solution, greatly shortening the process flow. The ammonia gas released during the evaporation process can be recovered and reused in the leaching process, realizing the recycling of ammonia medium, significantly improving environmental protection and economy. The system contains only ammonia, alkali, and target metal ions, without additional salt impurities, making washing easy to meet standards and avoiding the influence of impurity ions on the electrochemical performance of ternary materials.

[0036] (2) The present invention improves the crystal integrity of the cathode precursor through hydrothermal crystallization treatment, thereby obtaining a ternary cathode precursor with high tap density and better particle size distribution.

[0037] (3) By synergistically combining the ammonia stripping rate and the co-precipitation reaction, the ternary cathode precursor obtained by this invention has a spherical secondary particle morphology, and the primary crystals are plate-shaped and tightly packed. The particle structure is more regular than that of conventional ammonia leaching and direct precipitation. At the same time, this invention further narrows the particle size distribution of the precursor by adjusting the ammonia stripping-hydrothermal parameters, providing an effective way to achieve uniform and controllable micron-sized particles. Detailed Implementation

[0038] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0039] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0040] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0041] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0042] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined according to its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order in which they are written or in any order that does not conflict with the technology.

[0043] The nickel-cobalt-manganese-containing ammonia leaching solution used in the embodiments and comparative examples of this invention was prepared by the following method: Using calcined waste ternary cathode material as the material to be treated, an alkaline pre-leaching treatment is first performed, which can destroy the surface passivation layer, improve the leaching rate, and effectively remove impurities, reducing their interference with the subsequent leaching process. Then, grinding and high-pressure segmented leaching are performed in sequence to achieve efficient synergistic leaching of nickel, cobalt, and manganese, avoiding the problem of manganese being easily retained in the slag phase in traditional processes. Finally, the leaching solution containing nickel-cobalt-manganese complex is post-treated to obtain a high-purity nickel-cobalt-manganese product.

[0044] The mass concentrations of each ion in the nickel-cobalt-manganese ammonia leaching solution are as follows: Nickel: 38 g / L, Cobalt: 1.5 g / L, Manganese: 2.6 g / L, Sodium: 2.2 g / L, Sulfate: 182 g / L, Ammonium: 120 g / L.

[0045] Example 1 This embodiment provides a method for preparing a ternary cathode precursor using a nickel-cobalt-manganese-containing ammonia leaching solution with ammonia vapor extraction, characterized in that the method includes the following steps: A nickel-cobalt-manganese ammonia leaching solution was injected concurrently with a 25% (w / min) liquid alkali solution into a base solution (sodium hydroxide aqueous solution) with a pH of 10.5. The reaction was carried out for 22 hours under open ammonia stripping conditions, with the temperature controlled at 55℃ and the pH at 10.3~10.7, to obtain the reaction solution. After adjusting the pH of the reaction solution to 10, the solution was aged at 55°C for 12 hours to obtain an agglomeration precursor solution. The agglomeration precursor solution was subjected to hydrothermal crystallization treatment at 180℃ for 10 hours. After solid-liquid separation, the obtained solid material was washed with water 5 times and alkali 4 times alternately, with a solid-liquid mass ratio of 1:3, to obtain a ternary cathode precursor. The ternary cathode precursor includes primary grains and secondary particles formed by the accumulation of primary grains. The morphology of the primary grains is plate-like, and the thickness of the primary grains is 100nm~200nm.

[0046] Example 2 This embodiment provides a method for preparing a ternary cathode precursor using a nickel-cobalt-manganese-containing ammonia leaching solution with ammonia vapor extraction, characterized in that the method includes the following steps: A nickel-cobalt-manganese ammonia leaching solution was injected concurrently with a 20% (w / min) liquid alkali solution at pH 10 into a base solution (sodium hydroxide aqueous solution). The reaction was carried out for 25 hours under open ammonia stripping conditions, with the temperature controlled at 60℃ and the pH at 10-10.3, to obtain the reaction solution. After adjusting the pH of the reaction solution to 11.5, it was aged at 60℃ for 10 hours to obtain the agglomeration precursor solution. The agglomeration precursor solution was subjected to hydrothermal crystallization treatment at 100℃ for 32 hours. After solid-liquid separation, the obtained solid material was washed with water 5 times and alkali 4 times alternately, with a solid-liquid mass ratio of 1:2, to obtain a ternary cathode precursor. The ternary cathode precursor includes primary grains and secondary particles formed by the accumulation of primary grains. The morphology of the primary grains is plate-like, and the thickness of the primary grains is 50nm~200nm.

[0047] Example 3 This embodiment provides a method for preparing a ternary cathode precursor using a nickel-cobalt-manganese-containing ammonia leaching solution with ammonia vapor extraction, characterized in that the method includes the following steps: The nickel-cobalt-manganese-containing ammonia leaching solution was injected concurrently with a 20% (w / min) liquid alkali solution into a base solution (sodium hydroxide aqueous solution) with a pH of 10.8 at a flow rate of 2.2 mL / min. Under open ammonia stripping conditions, the temperature was controlled at 60℃ and the pH was controlled at 10.7~11 for 20 h to obtain the reaction solution. After adjusting the pH of the reaction solution to 10.2, it was aged at 50℃ for 15 hours to obtain the agglomeration precursor solution. The agglomeration precursor solution was subjected to hydrothermal crystallization treatment at 250℃ for 2 hours. After solid-liquid separation, the obtained solid material was washed with water 5 times and alkali 4 times alternately, with a solid-liquid mass ratio of 1:4, to obtain a ternary cathode precursor. The ternary cathode precursor includes primary grains and secondary particles formed by the accumulation of primary grains. The morphology of the primary grains is lamellar, and the thickness of the primary grains is 150nm~300nm.

[0048] Example 4 The only difference between this embodiment and Embodiment 1 is that the flow rate of the nickel-cobalt-manganese ammonia leaching solution is 1.5 mL / min; all other conditions and parameters are exactly the same as in Embodiment 1.

[0049] Example 5 The only difference between this embodiment and Embodiment 1 is that the flow rate of the nickel-cobalt-manganese ammonia leaching solution is 2.5 mL / min; all other conditions and parameters are exactly the same as in Embodiment 1.

[0050] Example 6 The only difference between this embodiment and Embodiment 1 is that the hydrothermal crystallization treatment temperature is 80°C, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0051] Example 7 The only difference between this embodiment and Embodiment 1 is that the hydrothermal crystallization treatment temperature is 300°C, while the other conditions and parameters are exactly the same as in Embodiment 1.

[0052] Comparative Example 1 This comparative example uses a commercially available NCM ternary cathode precursor.

[0053] Comparative Example 2 The only difference between this comparative example and Example 1 is that hydrothermal crystallization treatment is not performed; all other conditions and parameters are exactly the same as in Example 1.

[0054] Performance testing: The impurity content and tap density of the ternary cathode precursors obtained in the test examples and comparative examples are shown in Table 1. Table 1 As shown in Table 1, and based on Examples 1 to 7, the method for preparing ternary cathode precursors using ammonia leaching solution containing nickel, cobalt, and manganese provided by this invention can control the sodium content of the obtained ternary cathode precursor to within 400 ppm, the sulfur content to within 1250 ppm, and the tap density to reach 1.75 g / cm³. 3 The specific surface area can reach 24m². 2 / g or more.

[0055] Comparing Examples 1 and 4-5, it can be seen that in the method for preparing ternary cathode precursors using ammonia leaching solution containing nickel, cobalt, and manganese as described in this invention, the feed rate of the ammonia leaching solution containing nickel, cobalt, and manganese affects the performance of the obtained ternary cathode precursor. Controlling the flow rate of the ammonia leaching solution containing nickel, cobalt, and manganese at 1.8 mL / min to 2.2 mL / min yields a better-performing ternary cathode precursor. If the feed rate of the ammonia leaching solution containing nickel, cobalt, and manganese is too fast, a large amount of metal alkali ions will instantly enter the bottom solution. However, after the mixing and diffusion processes, local supersaturation of metal ions is easily formed, leading to explosive nucleation. A large number of fine crystal nuclei are rapidly generated, causing severe agglomeration and forming particles with excessively wide particle size distribution and irregular morphology. Simultaneously, excessively fast feeding may cause local pH fluctuations due to the buffering effect of ammonia, preventing some metal complexes from precipitating in time. Instead, they are encapsulated in the agglomerates, increasing impurity residue and reducing the crystallinity and tap density of the precursor. If the feed rate of the nickel-cobalt-manganese ammonia leaching solution is too slow, the crystal nucleation rate will be too slow, and particle growth will dominate. This will ultimately result in excessively large product particle size, and due to the excessively long reaction time, it will easily form a loose and uneven structure.

[0056] A comparison of Examples 1 and 6-7 shows that in the method for preparing ternary cathode precursors using ammonia leaching solution containing nickel, cobalt, and manganese as described in this invention, the hydrothermal crystallization temperature affects the performance of the obtained ternary cathode precursor. Controlling the hydrothermal crystallization temperature between 100℃ and 250℃ yields a ternary cathode precursor with better performance. If the hydrothermal crystallization temperature is too high, the product may undergo dehydration or partial hydrolysis, transforming into oxides or mixed compounds, destroying the original layered hydroxide structure, leading to a decrease in the material's specific surface area and abnormal tap density. If the hydrothermal crystallization temperature is too low, the precursor will have low crystallinity, numerous lattice defects, and irregular particle morphology, reducing the material's structural stability.

[0057] Comparing Example 1 and Comparative Example 1, it can be seen that the present invention uses a nickel-cobalt-manganese ammonia leaching solution to prepare a precursor under open ammonia stripping conditions. The nickel-cobalt-manganese ions in the nickel-cobalt-manganese ammonia leaching solution of the present invention exist in the form of complex ions. Under open ammonia stripping conditions, ammonia gas continuously volatilizes and escapes, the complex dissociates, and the metal ions undergo in-situ hydrolysis and co-precipitation to generate hydroxide precursors. The evaporated ammonia gas is absorbed and condensed, and then returned to the leaching section to prepare leaching agents. This achieves a closed-loop ammonia cycle while producing high-quality ternary cathode precursors.

[0058] As can be seen from the comparison between Example 1 and Comparative Example 2, the present invention, through hydrothermal crystallization treatment, transforms the amorphous / weakly crystalline agglomerative precursor into a high-quality hydroxide phase precursor with complete crystals, few internal defects, and high density through recrystallization and structural reorganization.

[0059] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a ternary cathode precursor by ammonia stripping using a nickel-cobalt-manganese-containing ammonia leaching solution, characterized in that, The method includes the following steps: Provide ammonia leaching solution containing nickel, cobalt, and manganese; A nickel-cobalt-manganese-containing ammonia leaching solution and liquid alkali were injected into the bottom solution in a parallel flow, and the reaction was carried out under open ammonia stripping conditions to obtain a reaction solution; After adjusting the pH of the reaction solution, it was aged to obtain an agglomeration precursor solution. The agglomeration precursor solution was subjected to hydrothermal crystallization treatment, and the solid-liquid separation was performed to obtain the ternary cathode precursor.

2. The method of claim 1, wherein, The mass concentration of nickel ions in the nickel-cobalt-manganese ammonia leaching solution is 30 g / L to 80 g / L. Preferably, the mass concentration of cobalt ions in the nickel-cobalt-manganese ammonia leaching solution is 1 g / L to 2 g / L; Preferably, the mass concentration of manganese ions in the nickel-cobalt-manganese ammonia leaching solution is 1 g / L to 5 g / L; Preferably, the mass concentration of sodium ions in the nickel-cobalt-manganese ammonia leaching solution is 1 g / L to 8 g / L; Preferably, the mass concentration of sulfate ions in the nickel-cobalt-manganese ammonia leaching solution is 150 g / L to 300 g / L; Preferably, the mass concentration of ammonium ions in the nickel-cobalt-manganese ammonia leaching solution is 100 g / L to 150 g / L; Preferably, the pH of the nickel-cobalt-manganese ammonia leaching solution is 8-10.

3. The method of claim 1 or 2, wherein, The mass percentage concentration of the liquid alkali is 20%~30%; Preferably, the pH of the base solution is 10-11.

4. The method according to any one of claims 1 to 3, characterized in that, The flow rate of the nickel-cobalt-manganese ammonia leaching solution is 1.8 mL / min to 2.2 mL / min.

5. The method according to any one of claims 1-4, characterized in that, The reaction temperature is 50℃~60℃; Preferably, the pH of the reaction is 10-11; Preferably, the reaction time is 20h to 25h.

6. The method according to any one of claims 1-5, characterized in that, The pH of the adjusted reaction solution is 10-11.

5.

7. The method according to any one of claims 1-6, characterized in that, The aging process is carried out at a temperature of 50℃~60℃; Preferably, the aging process takes 10 to 15 hours.

8. The method according to any one of claims 1-7, characterized in that, The temperature for the hydrothermal crystallization treatment is 100℃~180℃; Preferably, the hydrothermal crystallization treatment time is 2h to 32h.

9. The method according to any one of claims 1-8, characterized in that, The ternary cathode precursor obtained after hydrothermal crystallization is washed. Preferably, the washing process includes water washing and / or alkaline washing; Preferably, the solid-liquid mass ratio of the washing process is 1:(2~4).

10. The method according to any one of claims 1-9, characterized in that, The ternary cathode precursor includes primary grains and secondary particles formed by the stacking of primary grains; Preferably, the morphology of the primary grains includes lamellar and / or slatted shapes; Preferably, the thickness of the primary grain is 50 nm to 300 nm; Preferably, the specific surface area BET of the ternary positive electrode precursor is between 15 m 2 / g and 40 m 2 / g.

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