Preparation method for producing precursor based on spray pyrolysis method

Abstract

The invention relates to the technical field of ternary precursor materials, in particular to a preparation method for producing a precursor based on a spray pyrolysis method, an atomizer with an internal mixing type chamber is adopted, and the preparation method comprises the following steps: step 1, introducing high-speed carrier gas into the internal mixing type chamber in advance; step 2, after a first preset time, inputting a metal salt solution into the internal mixing type chamber, and meanwhile, continuously introducing high-speed carrier gas; step 3, after second preset time, inputting a precipitator into the inner mixing type chamber, continuously conveying the metal salt solution and high-speed carrier gas at the same time, depolymerizing particles formed by the metal salt solution and the precipitator by the high-speed carrier gas, and atomizing a liquid-solid mixture into liquid drops; 4, feeding the liquid drops into a spray pyrolysis furnace body through high-speed carrier gas, and performing thermal decomposition reaction on the liquid drops in the spray pyrolysis furnace body to form solid particles; 5, feeding the solid particles into a cyclone through high-speed carrier gas; and 6, collecting the solid particles treated by the cyclone through cloth bag dust collection equipment.

Description

Technical Field

[0001] This invention relates to the field of ternary precursor material technology, specifically to a method for preparing precursors based on spray pyrolysis. Background Technology

[0002] In the field of materials preparation, spray pyrolysis technology has gradually become a research hotspot in the precursor and cathode material industries in recent years due to its unique advantages. This technology sprays metal salt solutions, etc., into a high-temperature furnace to achieve instantaneous thermal decomposition, reaction, synthesis, or calcination, thereby obtaining metal oxide powder.

[0003] However, despite the promising prospects of spray pyrolysis technology, it is not yet fully developed and still faces many challenges in practical applications. During the pyrolysis process, secondary particle explosion often results in misshapen particles, easily forming hollow particles and leading to low tap density. This problem directly impacts the battery industry, causing uneven battery loading density, reduced capacity, and severely restricting the improvement of related product performance.

[0004] Among numerous related studies, patent CN118026292A discloses a ternary cathode material, its precursor, and a method for preparing the material and precursor. The method involves mixing a nickel-manganese-based mixed metal salt solution with a concentration of 80–500 g / L with an ammonium bicarbonate solution with a concentration of 200–400 g / L to obtain a mixed solution. Subsequently, the mixed solution is initially atomized at a first flow rate of 1–8 L / h for 3–5 s, and then the flow rate is increased to a second flow rate of 10–30 L / h for continued atomization. After atomization, the atomized solution is pyrolyzed at 300–850 °C for 10–90 s using an oxygen-containing carrier gas with a flow rate of 3–8 L / min, ultimately obtaining the cathode precursor material.

[0005] The above preparation method has significant drawbacks in practical operation. During the pretreatment stage of spraying, the mixing of the nickel-manganese-based mixed metal salt solution and the precipitant ammonium bicarbonate solution requires additional equipment, which undoubtedly increases production costs and is detrimental to large-scale mass production. Furthermore, the particle size of the precipitate formed during this mixing process is difficult to control precisely, easily clogging the nozzles and causing fluctuations in product quality, affecting production stability and product consistency.

[0006] Therefore, how to overcome the shortcomings of the existing technology is the subject of this invention. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing precursors based on spray pyrolysis.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing precursors based on spray pyrolysis, employing an atomizer with an internal mixing chamber, includes the following steps:

[0010] Step 1: Pre-introduce high-speed carrier gas into the internal mixing chamber;

[0011] Step 2: After the first predetermined time, a metal salt solution is introduced into the internal mixing chamber while the high-speed carrier gas is continuously introduced.

[0012] Step 3: After the second predetermined time, a precipitant is introduced into the internal mixing chamber, while the metal salt solution and the high-speed carrier gas are continuously delivered. The high-speed carrier gas deagglomerates the particles formed by the metal salt solution and the precipitant, and atomizes the liquid-solid mixture into droplets.

[0013] Step 4: The droplets are fed into the spray pyrolysis furnace body by the high-speed carrier gas, and the droplets undergo a thermal decomposition reaction in the spray pyrolysis furnace body to form solid particles;

[0014] Step 5: The solid particles are fed into the hydrocyclone using the high-speed carrier gas;

[0015] Step 6: Collect the solid particles processed by the cyclone separator using a bag filter dust collection device.

[0016] The atomizer is a conventional atomizer, and this application does not limit it.

[0017] The metal salt solution is a chloride-based, sulfuric acid-based, or nitrate-based salt. This part is not an innovation of this application and can be referred to existing precursor raw materials.

[0018] Each predetermined time is determined based on actual needs. Preferably, the first predetermined time is greater than 2 seconds, and the second predetermined time ranges from 2 to 5 seconds. To avoid misunderstanding, it is hereby clarified that the calculation of whether the second predetermined time has been reached begins after the metal salt solution is introduced into the internal mixing chamber.

[0019] Through the above scheme, on the one hand, the metal salt solution and the precipitant are mixed in the internal mixing chamber and depolymerized by high-speed carrier gas to form specific seed crystals (such as seed crystals of 300-800nm ​​as described below). The size of the seed crystals can be flexibly controlled, reducing the risk of clogging of the spray gun (or nozzle) in the atomizer, and the product performance can be more stable.

[0020] On the other hand, by using the (three-fluid) atomizer as the site of co-precipitation reaction, and combining it with the subsequent drying, pyrolysis and calcination processes of the spray pyrolysis furnace (the three correspond to thermal decomposition reactions), the two precursor preparation processes are integrated in one step, which integrates the co-precipitation method and the spray pyrolysis method that originally needed to be carried out in steps, greatly simplifying the operation process of producing the same substance using two methods.

[0021] High-speed carrier gas is introduced first to form a stable airflow field, providing power and environment for the subsequent atomization of the solution. When the subsequent metal salt solution and precipitant solution enter the atomization area, they can be immediately subjected to the shearing and impact of the high-speed carrier gas, achieving a good atomization effect and preventing large particles from forming during atomization, which would lead to insufficient sintering, crystallized salts, and hollow particles.

[0022] If the metal salt solution and precipitant are mixed first, the particle size of the precipitate formed during the mixing process is difficult to control precisely, easily clogging the nozzle and causing fluctuations in product quality, seriously affecting the stability of production and the consistency of products. In this application, the metal salt solution and precipitant are not mixed before being fed in, thus avoiding the above problems. At the same time, it avoids the need for additional mixing equipment, saving on this structural cost, which is conducive to mass production. The operation process is simple and beneficial to industrial production.

[0023] The pyrolysis products leave the spray pyrolysis furnace along with the high-speed carrier gas and enter a bag filter dust collector for collection, separating the solid particles from the gas. The exhaust gas is then treated before being discharged to meet environmental protection requirements. The collected solid particles are solid particles and high-vibration-compacted precursors.

[0024] The pyrolysis product is first fed into a hydrocyclone and then into a bag filter dust collector. Centrifugal force is used to separate larger particles, reducing the filtration load on the bag filter dust collector and extending its lifespan. Especially when the product particles have a high density and a wide particle size distribution, the hydrocyclone can efficiently pre-treat them and reduce the subsequent separation pressure.

[0025] This application enables the production of precursors having the following molecular formula: Ni 1-x-y Co x Mn y O2, where 0≤x<1, 0<y<1, 0<x+y<1; when x=0, the precursor is a nickel-manganese binary precursor or a lithium-rich manganese-based precursor.

[0026] In a further technical solution, ammonia is used as the precipitant to avoid introducing impurities.

[0027] In some embodiments, the precipitant is one or more of ammonia, sodium hydroxide, and oxalic acid.

[0028] A further technical solution is that the concentration range of the metal salt solution is 1-4 mol / L (or 1 mol / L-4 mol / L), and the concentration range of the precipitant is 0.5-2 mol / L, in order to prevent the precipitation rate from being too fast and the precipitation amount from being too large, thus avoiding nozzle clogging.

[0029] In some embodiments, the concentration range of the metal salt solution is 1-6 mol / L, the concentration range of the precipitant is 0.5-3.0 mol / L, and the total molar amount of the main element is ≥ the stoichiometric amount required for the precipitant to react completely (in practice, the total molar amount of the main element is controlled to be twice that of the precipitant).

[0030] A further technical solution is that the pH value of the droplets is in the range of 5-8. Below this range, it is difficult to form a metal salt solution precipitate; above this range, the metal salt solution is prone to complete precipitation, resulting in excessively large particles, which leads to reduced gas flow depolymerization efficiency, clogging of the nozzle, and denaturation of the oxide precursor.

[0031] In a further technical solution, in steps one to four, the temperature range of the high-speed carrier gas is 50℃-80℃.

[0032] In steps two and three, the temperature range of the metal salt solution is 30℃-60℃;

[0033] In step three, the temperature range of the precipitant is 30℃-60℃;

[0034] In steps one through three, the temperature range of the internal mixing chamber is 40℃-80℃.

[0035] Because the contact time between the precipitant and the metal salt solution is relatively short, this section limits the temperature range of the high-speed carrier gas, the metal salt solution, and the precipitant in order to accelerate the reaction rate and ensure complete reaction of the precipitant. It should be noted that, using the precipitant as an example, although not mentioned in step four, the precipitant can be continuously added to continuously produce the precursor product, and the temperature of the precipitant is always within the aforementioned limits.

[0036] By limiting the temperature range of the internal mixing chamber to 40℃-80℃, the reaction speed is faster and the precipitant reacts completely, increasing the probability of particles forming high-compact products. At the same time, it reduces the side reactions of the precipitant inside the furnace, thereby reducing energy consumption.

[0037] In a further technical solution, in steps one to three, the pressure range of the high-speed carrier gas is 0.7 MPa to 0.8 MPa, and the flow rate range of the high-speed carrier gas is 10 m³ / s. 3 / H-20m 3 / H. Under these conditions, after mixing with three fluids (high-speed carrier gas, precipitant solvent, and metal salt solution), the resulting seed crystals are typically 300-800 nm in size. It should be noted that seed crystals smaller than 300 nm will result in hollow interiors in the spray spheres; seed crystals larger than 800 nm will cause the spray pyrolysis spheres to crack or develop protrusions and grooves on their surface.

[0038] By controlling the seed crystal size range of 300-800 nm, high-tap precursors can be produced. Compared to low-tap precursors prepared by other spray pyrolysis methods, high-tap precursors can improve energy density, and higher tap density means that more active material can be packed in the same volume. High-tap precursors can also improve electrical conductivity. By controlling the precursor particle size and distribution, a more uniform and compact structure can be obtained, which is beneficial to improving the electron transport efficiency within the material. In addition, a reasonable particle size design can make the contact between active materials and between active materials and current collectors more compact and stable.

[0039] In some implementations, the pressure range of the high-speed carrier gas is 0.3 MPa to 0.8 MPa.

[0040] In a further technical solution, the flow rate of the high-speed carrier gas remains unchanged in steps one through six;

[0041] In steps two and three, the flow rate of the metal salt solution remains constant;

[0042] In step three, the flow rate of the precipitant remains constant.

[0043] The stable flow rate of the three fluids ensures a constant concentration ratio and contact state of the reactants in the reaction zone, reducing local reaction differences caused by fluctuations in raw material supply. This facilitates the generation of precursor particles with uniform particle size distribution and regular morphology, laying the foundation for obtaining solid particles with high tap density. Simultaneously, a stable carrier gas flow rate ensures consistent atomization, stabilizing droplet size and distribution, further improving the performance consistency between product batches.

[0044] To illustrate again using the example of a precipitant, in other steps (such as steps four to six), the precipitant can be continuously added to continuously produce the precursor product, and the flow rate of the precipitant remains constant during this period.

[0045] In a further technical solution, the high-speed carrier gas is set to oxygen. When a mixed solution of nickel nitrate, cobalt nitrate, and manganese nitrate is used as the metal salt solution, oxygen as the carrier gas can promote the full oxidation of metal ions to a stable high valence state, ensuring the integrity of the oxide precursor structure and meeting the purity requirements of the process for the oxidation atmosphere.

[0046] In some implementations, the high-speed carrier gas is configured as compressed air.

[0047] In a further technical solution, the flow rate of the metal salt solution is in the range of 12L / H-30L / H, the flow rate of the precipitant is in the range of 4L / H-10L / H, and the flow rate ratio of the metal salt solution to the precipitant is 3:1.

[0048] This section limits the flow rates of the metal salt solution and the precipitant to ensure complete consumption of the precipitant, allowing the final metal ions to fully adhere to the precipitate surface, resulting in denser spheres and higher compaction. Under this limitation, the total number of moles of metal ions precipitating in the metal salt solution is 30%-40% of the total number of moles of metal ions in the solution.

[0049] In a further technical solution, in step four, the droplets are sequentially dried, pyrolyzed, and calcined within the spray pyrolysis furnace to form the solid particles.

[0050] During the drying process, the drying temperature is 200-300℃;

[0051] During the pyrolysis treatment stage, the pyrolysis temperature is 500-900℃;

[0052] During the calcination process, the calcination temperature is 800-1000℃.

[0053] Droplets containing co-precipitated particles are carried by a high-speed carrier gas and enter the drying section of the spray pyrolysis furnace from the atomizer nozzle. The drying temperature is 200-300℃, which allows the moisture to evaporate slowly, reducing the probability of atomized particles exploding. Combined with the crystal nuclei formed by precipitation, initial solid particles are formed. The dried solid particles enter the pyrolysis section, where the pyrolysis temperature is 500-900℃, allowing the crystal nuclei to react fully and form stable grains. The external salt is fully wrapped around the grains. The intermediate after pyrolysis enters the high-temperature calcination section, where the calcination temperature is 800-1000℃. Crystal growth, phase transformation, or sintering occurs in a continuous carrier gas atmosphere, forming uniform secondary particles with the target phase and morphology.

[0054] The terms "first," "second," etc., used in this article do not specifically refer to order or sequence, nor are they intended to limit this case; they are merely used to distinguish components or operations described using the same technical terms.

[0055] The terms "connection" or "positioning" as used in this article can refer to two or more components or devices making direct physical contact with each other, or making indirect physical contact with each other, or to two or more components or devices operating or moving with each other.

[0056] The terms “include,” “including,” and “have” used in this article are all open-ended, meaning they include but are not limited to.

[0057] Unless otherwise specified, the terms used herein generally have their ordinary meaning in the context of the art, the subject matter, and the specific context. Certain terms used to describe this case will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing this case.

[0058] The terms “front,” “back,” “up,” “down,” “left,” and “right” used in this article are directional terms. In this case, they are only used to describe the positional relationship between the structures and are not intended to limit the specific direction of the protection scheme or its actual implementation.

[0059] The working principle and advantages of this invention are as follows:

[0060] During implementation, on the one hand, the metal salt solution and precipitant are mixed in an internal mixing chamber and depolymerized by a high-speed carrier gas to form specific seed crystals (such as the 300-800nm ​​seed crystals described below). The seed crystal size can be flexibly controlled, reducing the risk of clogging in the spray gun (or nozzle) of the atomizer, and the product performance can be more stable. On the other hand, by using the (three-fluid) atomizer as the site of the co-precipitation reaction, combined with the subsequent drying, pyrolysis, and calcination processes of the spray pyrolysis furnace (the three correspond to thermal decomposition reactions), the two precursor preparation processes are integrated in one step. This integrates the co-precipitation method and the spray pyrolysis method, which originally required separate steps, and greatly simplifies the operation process of producing the same substance using two methods.

[0061] High-speed carrier gas is introduced first to form a stable airflow field, providing power and environment for the subsequent atomization of the solution. When the subsequent metal salt solution and precipitant solution enter the atomization area, they can be immediately subjected to the shearing and impact of the high-speed carrier gas, achieving a good atomization effect and preventing large particles from forming during atomization, which would lead to insufficient sintering, crystallized salts, and hollow particles.

[0062] If the metal salt solution and precipitant are mixed first, the particle size of the precipitate formed during the mixing process is difficult to control precisely, easily clogging the nozzle and causing fluctuations in product quality, seriously affecting the stability of production and the consistency of products. In this application, the metal salt solution and precipitant are not mixed before being fed in, thus avoiding the above problems. At the same time, it avoids the need for additional mixing equipment, saving on this structural cost, which is conducive to mass production. The operation process is simple and beneficial to industrial production.

[0063] The pyrolysis products leave the spray pyrolysis furnace along with the high-speed carrier gas and enter a bag filter dust collector for collection, separating the solid particles from the gas. The exhaust gas is then treated before being discharged to meet environmental protection requirements. The collected solid particles are solid particles and high-vibration-compacted precursors.

[0064] The pyrolysis product is first fed into a hydrocyclone and then into a bag filter dust collector. Centrifugal force is used to separate larger particles, reducing the filtration load on the bag filter dust collector and extending its lifespan. Especially when the product particles have a high density and a wide particle size distribution, the hydrocyclone can efficiently pre-treat them and reduce the subsequent separation pressure. Attached Figure Description

[0065] Figure 1This is a flowchart of the preparation method of precursor production based on spray pyrolysis according to an embodiment of the present invention;

[0066] Figure 2 This is a SEM image of Example 1;

[0067] Figure 3 This is a SEM image of Example 2;

[0068] Figure 4 This is a SEM image of Example 3;

[0069] Figure 5 This is a SEM image of Example 4;

[0070] Figure 6 This is the SEM image of Comparative Example 1. Detailed Implementation

[0071] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0072] Example: The present invention will be clearly described below with illustrations and detailed description. Any person skilled in the art who understands the examples of the present invention can make changes and modifications based on the technology taught in the present invention without departing from the spirit and scope of the present invention.

[0073] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of this work. Singular forms such as “a,” “this,” “this,” “the,” and “the” as used herein also include plural forms.

[0074] See Figure 1 A method for preparing precursors based on spray pyrolysis, employing an atomizer with an internal mixing chamber, the preparation method comprising:

[0075] Step 1: Pre-introduce high-speed carrier gas into the internal mixing chamber;

[0076] Step 2: After the first predetermined time, a metal salt solution is introduced into the internal mixing chamber while the high-speed carrier gas is continuously introduced.

[0077] Step 3: After the second predetermined time, a precipitant is introduced into the internal mixing chamber, while the metal salt solution and the high-speed carrier gas are continuously delivered. The high-speed carrier gas deagglomerates the particles formed by the metal salt solution and the precipitant, and atomizes the liquid-solid mixture into droplets.

[0078] Step 4: The droplets are fed into the spray pyrolysis furnace body by the high-speed carrier gas, and the droplets undergo a thermal decomposition reaction in the spray pyrolysis furnace body to form solid particles;

[0079] Step 5: The solid particles are fed into the hydrocyclone using the high-speed carrier gas;

[0080] Step 6: Collect the solid particles processed by the cyclone separator using a bag filter dust collection device.

[0081] The atomizer is a conventional atomizer, and this embodiment is not limited to it.

[0082] The metal salt solution is a chloride-based, sulfuric acid-based, or nitrate-based salt. This part is not an innovation of this application and can be referred to existing precursor raw materials.

[0083] Each predetermined time is determined based on actual needs. Preferably, the first predetermined time is greater than 2 seconds, and the second predetermined time ranges from 2 to 5 seconds. To avoid misunderstanding, it is hereby clarified that the calculation of whether the second predetermined time has been reached begins after the metal salt solution is introduced into the internal mixing chamber.

[0084] Through the above scheme, on the one hand, the metal salt solution and the precipitant are mixed in the internal mixing chamber and depolymerized by high-speed carrier gas to form specific seed crystals (such as seed crystals of 300-800nm ​​as described below). The size of the seed crystals can be flexibly controlled, reducing the risk of clogging of the spray gun (or nozzle) in the atomizer, and the product performance can be more stable.

[0085] On the other hand, by using the (three-fluid) atomizer as the site of co-precipitation reaction, and combining it with the subsequent drying, pyrolysis and calcination processes of the spray pyrolysis furnace (the three correspond to thermal decomposition reactions), the two precursor preparation processes are integrated in one step, which integrates the co-precipitation method and the spray pyrolysis method that originally needed to be carried out in steps, greatly simplifying the operation process of producing the same substance using two methods.

[0086] High-speed carrier gas is introduced first to form a stable airflow field, providing power and environment for the subsequent atomization of the solution. When the subsequent metal salt solution and precipitant solution enter the atomization area, they can be immediately subjected to the shearing and impact of the high-speed carrier gas, achieving a good atomization effect and preventing large particles from forming during atomization, which would lead to insufficient sintering, crystallized salts, and hollow particles.

[0087] The metal salt solution is introduced before the precipitant to ensure atomization effect and prevent the precipitant from entering the internal mixing chamber first, which could easily lead to excessive precipitant and the formation of large particles inside when the molten metal is introduced again, clogging the spray gun.

[0088] If the metal salt solution and precipitant are mixed first, the particle size of the precipitate formed during the mixing process is difficult to control precisely, easily clogging the nozzle and causing fluctuations in product quality, seriously affecting the stability of production and the consistency of products. In this embodiment, the metal salt solution and precipitant are not mixed before being fed in, thus avoiding the above problems. At the same time, it avoids the need to add mixing equipment, saving this structural cost, which is conducive to mass production. The operation process is simple and conducive to industrial production.

[0089] The pyrolysis products leave the spray pyrolysis furnace along with the high-speed carrier gas and enter a bag filter dust collector for collection, separating the solid particles from the gas. The exhaust gas is then treated before being discharged to meet environmental protection requirements. The collected solid particles are solid particles and high-vibration-compacted precursors.

[0090] The pyrolysis product is first fed into a hydrocyclone and then into a bag filter dust collector. Centrifugal force is used to separate larger particles, reducing the filtration load on the bag filter dust collector and extending its lifespan. Especially when the product particles have a high density and a wide particle size distribution, the hydrocyclone can efficiently pre-treat them and reduce the subsequent separation pressure.

[0091] This embodiment can produce a precursor with the following molecular formula: Ni 1-x-y Co x Mn y O2, where 0≤x<1, 0<y<1, 0<x+y<1; when x=0, the precursor is a nickel-manganese binary precursor or a lithium-rich manganese-based precursor.

[0092] To aid understanding, a supplementary explanation is provided for step three: An excess of metal salt solution is used, and the molar amount of metal salt precipitated by the precipitant is 30-40% (preferred range) of the total molar amount. The remaining metal salt encapsulates the depolymerized seed crystals in solution form. The high-speed carrier gas depolymerizes these seed-solution encapsulated aggregates and atomizes them into droplets containing solid particles. These droplets are then torn apart and atomized again outside the internal mixing chamber.

[0093] In this embodiment, ammonia is used as the precipitant to avoid introducing impurities.

[0094] In some embodiments, the precipitant is one or more of ammonia, sodium hydroxide, and oxalic acid.

[0095] In this embodiment, the concentration range of the metal salt solution is 1-4 mol / L (or 1 mol / L-4 mol / L), and the concentration range of the precipitant is 0.5-2 mol / L, in order to prevent the precipitation rate from being too fast and the precipitation amount from being too large, thus avoiding nozzle clogging.

[0096] In some embodiments, the concentration range of the metal salt solution is 1-6 mol / L, the concentration range of the precipitant is 0.5-3.0 mol / L, and the total molar amount of the main element is ≥ the stoichiometric amount required for the precipitant to react completely (in practice, the total molar amount of the main element is controlled to be twice that of the precipitant).

[0097] In this embodiment, the pH value of the droplets is in the range of 5-8. Below this range, it is difficult to form a metal salt solution precipitate; above this range, the metal salt solution is prone to complete precipitation, resulting in excessively large particles, which leads to reduced gas flow depolymerization efficiency, clogging of the nozzle, and denaturation of the oxide precursor.

[0098] In this embodiment, the temperature range of the high-speed carrier gas in steps one to four is 50℃-80℃;

[0099] In steps two and three, the temperature range of the metal salt solution is 30℃-60℃;

[0100] In step three, the temperature range of the precipitant is 30℃-60℃;

[0101] In steps one through three, the temperature range of the internal mixing chamber is 40℃-80℃.

[0102] Because the contact time between the precipitant and the metal salt solution is relatively short, this section limits the temperature range of the high-speed carrier gas, the metal salt solution, and the precipitant in order to accelerate the reaction rate and ensure complete reaction of the precipitant. It should be noted that, using the precipitant as an example, although not mentioned in step four, the precipitant can be continuously added to continuously produce the precursor product, and the temperature of the precipitant is always within the aforementioned limits.

[0103] By limiting the temperature range of the internal mixing chamber to 40℃-80℃, the reaction speed is faster and the precipitant reacts completely, increasing the probability of particles forming high-compact products. At the same time, it reduces the side reactions of the precipitant inside the furnace, thereby reducing energy consumption.

[0104] In this embodiment, in steps one to three, the pressure range of the high-speed carrier gas is 0.7 MPa to 0.8 MPa, and the flow rate range of the high-speed carrier gas is 10 m³ / s. 3 / H-20m 3 / H. Under these conditions, after mixing with three fluids (high-speed carrier gas, precipitant solvent, and metal salt solution), the resulting seed crystals are typically 300-800 nm in size. It should be noted that seed crystals smaller than 300 nm will result in hollow interiors in the spray spheres; seed crystals larger than 800 nm will cause the spray pyrolysis spheres to crack or develop protrusions and grooves on their surface.

[0105] By controlling the seed crystal size range of 300-800 nm, high-tap precursors can be produced. Compared to low-tap precursors prepared by other spray pyrolysis methods, high-tap precursors can improve energy density, and higher tap density means that more active material can be packed in the same volume. High-tap precursors can also improve electrical conductivity. By controlling the precursor particle size and distribution, a more uniform and compact structure can be obtained, which is beneficial to improving the electron transport efficiency within the material. In addition, a reasonable particle size design can make the contact between active materials and between active materials and current collectors more compact and stable.

[0106] In some embodiments, the pressure range of the high-speed carrier gas is 0.3 MPa to 0.8 MPa.

[0107] In this embodiment, the flow rate of the high-speed carrier gas remains unchanged in steps one through six;

[0108] In steps two and three, the flow rate of the metal salt solution remains constant;

[0109] In step three, the flow rate of the precipitant remains constant.

[0110] The stable flow rate of the three fluids ensures a constant concentration ratio and contact state of the reactants in the reaction zone, reducing local reaction differences caused by fluctuations in raw material supply. This facilitates the generation of precursor particles with uniform particle size distribution and regular morphology, laying the foundation for obtaining solid particles with high tap density. Simultaneously, a stable carrier gas flow rate ensures consistent atomization, stabilizing droplet size and distribution, further improving the performance consistency between product batches.

[0111] To illustrate again using the example of a precipitant, in other steps (such as steps four to six), the precipitant can be continuously added to continuously produce the precursor product, and the flow rate of the precipitant remains constant during this period.

[0112] In this embodiment, the high-speed carrier gas is oxygen. When a mixed solution of nickel nitrate, cobalt nitrate, and manganese nitrate is used as the metal salt solution, oxygen as the carrier gas can promote the full oxidation of metal ions to a stable high valence state, ensuring the integrity of the oxide precursor structure and meeting the purity requirements of the process for the oxidation atmosphere.

[0113] In some embodiments, the high-speed carrier gas is configured as compressed air.

[0114] In this embodiment, the flow rate of the metal salt solution ranges from 12 L / H to 30 L / H, the flow rate of the precipitant ranges from 4 L / H to 10 L / H, and the flow rate ratio of the metal salt solution to the precipitant is 3:1.

[0115] This section limits the flow rates of the metal salt solution and the precipitant to ensure complete consumption of the precipitant, allowing the final metal ions to fully adhere to the precipitate surface, resulting in denser spheres and higher compaction. Under this limitation, the total number of moles of metal ions precipitating in the metal salt solution is 30%-40% of the total number of moles of metal ions in the solution.

[0116] In this embodiment, in step four, the droplets are sequentially dried, pyrolyzed, and calcined inside the spray pyrolysis furnace to form the solid particles;

[0117] During the drying process, the drying temperature is 200-300℃;

[0118] During the pyrolysis treatment stage, the pyrolysis temperature is 500-900℃;

[0119] During the calcination process, the calcination temperature is 800-1000℃.

[0120] Droplets containing co-precipitated particles are carried by a high-speed carrier gas and enter the drying section of the spray pyrolysis furnace from the atomizer nozzle. The drying temperature is 200-300℃, which allows the moisture to evaporate slowly, reducing the probability of atomized particles exploding. Combined with the crystal nuclei formed by precipitation, initial solid particles are formed. The dried solid particles enter the pyrolysis section, where the pyrolysis temperature is 500-900℃, allowing the crystal nuclei to react fully and form stable grains. The external salt is fully wrapped around the grains. The intermediate after pyrolysis enters the high-temperature calcination section, where the calcination temperature is 800-1000℃. Crystal growth, phase transformation, or sintering occurs in a continuous carrier gas atmosphere, forming uniform secondary particles with the target phase and morphology.

[0121] The following provides specific embodiments and comparative examples for illustration:

[0122] Example 1

[0123] (1) Prepare a 100L mixed solution of nickel nitrate, cobalt nitrate and manganese nitrate; the molar percentage of nickel, cobalt and manganese elements is 5:2:3; the concentration of the metal salt solution is 1mol / L; the temperature of the metal salt solution is 40℃; prepare a precipitant with a concentration of 0.5mol / L using ammonia water at a temperature of 40℃; heat the compressed air (high-speed carrier gas) to 60℃.

[0124] (2) Adjust the high-speed carrier gas flow rate to 12 m3 / H and the pressure to 0.75 MPa. Pre-pump the liquid particle size collection tank for 3 seconds. Then, pre-pump the metal salt solution for 3 seconds before the precipitant, with a flow rate of 12 L / H. Finally, pump the precipitant, with a flow rate of 4 L / H. Spray for 5 minutes and test the spray gun jet D50.

[0125] (3) After completing the second step above, the atomizing gun is introduced into the spray pyrolysis furnace and high-speed carrier gas, metal salt solution and precipitant are continuously introduced, with the same parameters as the second step.

[0126] (4) Set the drying temperature of the spray pyrolysis furnace to 220℃, the pyrolysis temperature to 550℃, and the calcination temperature to 870℃.

[0127] (5) Collect precursor materials, take scanning electron microscope images, and see... Figure 2 .

[0128] During the preparation of the precursor, its tapping performance and morphology were controlled, and the clogging of the nozzle was recorded. The tapping performance data and clogging records are shown in Table 1.

[0129] Example 2

[0130] Compared with Example 1, the following changes were made:

[0131] The concentration of the metal salt solution was adjusted to 2 mol / L; the concentration of the precipitant was adjusted to 1 mol / L.

[0132] Collect atomized oxide precursor materials, take scanning electron microscope images, see... Figure 3 .

[0133] During the preparation of the precursor, its tapping performance and morphology were controlled, and the clogging of the nozzle was recorded. The tapping performance data and clogging records are shown in Table 1.

[0134] Example 3

[0135] Compared with Example 1, the following changes were made:

[0136] The concentration of the metal salt solution was adjusted to 3 mol / L; the concentration of the precipitant was adjusted to 1.5 mol / L.

[0137] Collect atomized oxide precursor materials, take scanning electron microscope images, see... Figure 4 .

[0138] During the preparation of the precursor, its tapping performance and morphology were controlled, and the clogging of the nozzle was recorded. The tapping performance data and clogging records are shown in Table 1.

[0139] Example 4

[0140] Compared with Example 3, the following changes were made:

[0141] The temperature of the metal salt solution was adjusted to 55℃, the temperature of the precipitant was adjusted to 55℃, and the temperature of the compressed air was adjusted to 70℃.

[0142] Collect atomized oxide precursor materials, take scanning electron microscope images, see... Figure 5 .

[0143] During the preparation of the precursor, its tapping performance and morphology were controlled, and the clogging of the nozzle was recorded. The tapping performance data and clogging records are shown in Table 1.

[0144] Comparative Example 1

[0145] (1) Prepare a 100L mixed solution of nickel nitrate, cobalt nitrate and manganese nitrate, with a molar percentage of nickel, cobalt and manganese elements of 5:2:3, a metal salt solution concentration of 3mol / L, and a metal salt solution temperature of 55℃.

[0146] (2) Inject the mixed solution into the atomizer. The carrier gas is compressed air, and the spray carrier gas flow rate is 12 m3 / h.

[0147] (3) Set the drying temperature of the spray pyrolysis furnace to 220℃, the pyrolysis temperature to 550℃, and the calcination temperature to 870℃.

[0148] (4) Collect the oxide precursor material, take a scanning electron microscope image, and see... Figure 6 .

[0149] During the preparation of the precursor, its tapping performance and morphology were controlled, and the clogging of the nozzle was recorded. The tapping performance data and clogging records are shown in Table 1.

[0150] Table 1. Precursor Indices of Spray Pyrolysis

[0151]

[0152] Comparing Examples 1, 2, and 3 in Table 1, we found that: ① As the concentrations of molten metal and precipitant increased, the spray gun jet D50 increased accordingly, and the cyclone collector D50 also gradually increased; ② The compaction gradually increased, but the increase was not significant. Compared with Comparative Example 1, the precipitant participated in the reaction, which significantly increased the compaction.

[0153] Comparing Examples 3 and 4, although the temperatures of the metal salt solution, precipitant, and high-speed carrier gas were increased, the changes in the spray gun jet D50 and cyclone collection D50 were not significant, while the compaction was significantly improved. This indicates that increasing the temperature of the metal salt solution and precipitant resulted in more complete precipitation and denser seed crystals.

[0154] Figure 2 , Figure 3 , Figure 4 , Figure 5 These four and Figure 6 The scanning electron microscope comparison showed that the formed grains were denser and there were fewer hollow spheres.

[0155] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing precursors based on spray pyrolysis, characterized in that: The preparation method employs an atomizer with an internal mixing chamber and includes: Step 1: Pre-introduce high-speed carrier gas into the internal mixing chamber; Step 2: After the first predetermined time, a metal salt solution is introduced into the internal mixing chamber while the high-speed carrier gas is continuously introduced. Step 3: After the second predetermined time, a precipitant is introduced into the internal mixing chamber, while the metal salt solution and the high-speed carrier gas are continuously delivered. The high-speed carrier gas deagglomerates the particles formed by the metal salt solution and the precipitant, and atomizes the liquid-solid mixture into droplets. Step 4: The droplets are fed into the spray pyrolysis furnace body by the high-speed carrier gas, and the droplets undergo a thermal decomposition reaction in the spray pyrolysis furnace body to form solid particles; Step 5: The solid particles are fed into the hydrocyclone using the high-speed carrier gas; Step 6: Collect the solid particles processed by the cyclone separator using a bag filter dust collection device.

2. The method for preparing precursors based on spray pyrolysis according to claim 1, characterized in that: The precipitant used is ammonia water to avoid introducing impurities.

3. The method for preparing precursors based on spray pyrolysis according to claim 1, characterized in that: The concentration range of the metal salt solution is 1-4 mol / L, and the concentration range of the precipitant is 0.5-2 mol / L, to prevent the precipitation rate from being too fast and the amount of precipitation from being too large, thus avoiding nozzle clogging.

4. The method for preparing precursors based on spray pyrolysis according to claim 1, characterized in that: The pH value of the droplets is in the range of 5-8.

5. The method for preparing precursors based on spray pyrolysis according to claim 1, characterized in that: In steps one through four, the temperature range of the high-speed carrier gas is 50℃-80℃; In steps two and three, the temperature range of the metal salt solution is 30℃-60℃; In step three, the temperature range of the precipitant is 30℃-60℃; In steps one through three, the temperature range of the internal mixing chamber is 40℃-80℃.

6. The method for preparing precursors based on spray pyrolysis according to claim 1, characterized in that: In steps one through three, the pressure range of the high-speed carrier gas is 0.7 MPa to 0.8 MPa, and the flow rate range of the high-speed carrier gas is 10 m³ / H to 20 m³ / H.

7. The method for preparing precursors based on spray pyrolysis according to claim 1, characterized in that: In steps one through six, the flow rate of the high-speed carrier gas remains constant; In steps two and three, the flow rate of the metal salt solution remains constant; In step three, the flow rate of the precipitant remains constant.

8. The method for preparing precursors based on spray pyrolysis according to claim 1, characterized in that: The high-speed carrier gas is set to oxygen.

9. The method for preparing precursors based on spray pyrolysis according to claim 1, characterized in that: The flow rate of the metal salt solution ranges from 12 L / H to 30 L / H, the flow rate of the precipitant ranges from 4 L / H to 10 L / H, and the flow rate ratio of the metal salt solution to the precipitant is 3:

1.

10. The method for preparing precursors based on spray pyrolysis according to claim 1, characterized in that: In step four, the droplets are sequentially dried, pyrolyzed, and calcined inside the spray pyrolysis furnace to form the solid particles. During the drying process, the drying temperature is 200-300℃; During the pyrolysis treatment stage, the pyrolysis temperature is 500-900℃; During the calcination process, the calcination temperature is 800-1000℃.

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