Multi-element precursor for a porous structure and method for producing the same

Abstract

The application discloses a porous multi-element precursor with a loose porous structure, and a chemical general formula is Ni x Mn y Mo z (OH)2, and has a structure-controllable feature. The application further discloses a preparation method of the porous multi-element precursor, and comprises the following steps: configuring solution A, solution B, solution C and solution D; adding pure water into a reaction kettle, introducing nitrogen for replacement, adding solution B and solution C as a bottom liquid by heating, adding solution A for nucleation, adding solution B and solution C, introducing a dopant D to obtain a loose porous precursor slurry when the nucleation is finished; and performing solid-liquid separation, washing, drying and sieving on the precursor slurry to obtain the multi-element precursor. The process is easy to control, is suitable for industrial production, and solves the problem that the internal structure of the precursor is uncontrollable by synergistically controlling the oxygen content and the structure regulator.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery cathode material technology, and relates to a loose porous multi-component precursor for lithium-ion batteries, as well as a method for preparing the loose porous multi-component precursor for lithium-ion batteries. Background Technology

[0002] Lithium-ion batteries, as a highly efficient, lightweight, high-energy-density, and rechargeable energy storage solution, have become an indispensable energy medium in modern society. They are widely used in mobile electronic devices, electric vehicles, energy storage systems, and renewable energy facilities, profoundly impacting our lifestyles and the environment. With the continuous improvement of people's quality of life, the demand for cathode materials is also increasing, making it imperative to further improve cathode material performance. Currently, cathode materials face the following problems: 1. The continuous insertion and extraction of lithium ions during cycling causes the cathode material to expand and contract, inducing mechanical stress within the material. Repeated mechanical stress leads to instability in the microstructure of the cathode material, ultimately resulting in cracks and particle separation, reducing battery life and performance; 2. Side reactions such as changes in the cathode material structure, the formation of solid-phase interfaces, and electrolyte penetration into cracks can lead to performance degradation. Furthermore, the migration rate of lithium ions is closely related to the morphology and packing density of primary particles. Tight packing increases resistance during ion migration, significantly affecting the material's rate performance. As is well known, the morphology of cathode materials is largely determined by the upstream precursor. Compared to the surface morphology of the precursor, the internal morphology is more important for the sintering performance of the cathode material. Therefore, in the ternary precursor co-precipitation method, which is the most widely used industrial technology, it is particularly important to add structure modifiers to achieve controllable internal structure of the product.

[0003] Chinese patent CN115340133A, published on November 15, 2022, discloses a molybdenum-doped nickel-rich ternary precursor and its preparation method. In the preparation of the ternary precursor, the additives used have abundant carboxylic acid groups in their molecular structure to limit the growth of primary particles. Mo doping reduces the formation of isolated oxygen, effectively preventing the loss of lattice oxygen during long-term cycling and stabilizing the structure. However, the additives used in this paper increase production and transportation costs, and the newly introduced additives can easily affect product quality by introducing impurities. Chinese patent CN115924988A, published on April 7, 2023, discloses a core-shell structured ternary precursor, its preparation method, and single crystal. A small amount of air is introduced to form a core porosity effect, and the outer shell is doped with elements to prepare a thick serrated shell layer for single crystal morphology. Although the natural oxidation method used in this paper achieves the internal porosity effect, the degree of oxidation is difficult to control, and the morphology is significantly affected by different manganese contents, which is detrimental to batch stability and makes subsequent process scale-up difficult.

[0004] Currently, layered oxide precursor materials prepared by co-precipitation are prone to multi-sphere adhesion at small particle sizes, resulting in poor sphericity and easy formation of micropowder after sintering. Furthermore, with prolonged synthesis time and increased solid content, the secondary spheres gradually compact, leading to uneven lithium mixing and difficulties in lithium ion insertion / extraction in the sintered cathode material. The compact structure also makes it difficult to release internal stress, causing microcracks within the grains. There is an urgent need to develop precursors with simple operation processes and controllable internal structures to promote more uniform contact during lithium mixing to reduce residual lithium on the surface, effectively release stress during cycling, promote rapid lithium ion migration during charge and discharge, and improve the electrochemical performance of the material. Summary of the Invention

[0005] The primary objective of this invention is to provide a loose, porous, multi-element precursor with a controllable structure.

[0006] The second objective of this invention is to provide a method for preparing a loose and porous multi-element precursor, which solves the problem of uncontrollable internal structure of the precursor prepared in the prior art by synergistic control of oxygen content and structure regulator.

[0007] The first technical solution adopted in this invention is a multi-element precursor with a loose and porous structure for lithium-ion batteries, wherein the general chemical formula of the precursor is Ni. x Mn y Mo z (OH)₂, of which 0.5 <x<0.9,0<y<0.5,0<z<0.05,x+z+y=1。

[0008] The second technical solution adopted in this invention is a method for preparing a multi-element precursor with a loose porous structure for lithium-ion batteries, as described above, comprising the following steps:

[0009] Step 1: Prepare nickel and manganese metal salt solution A; prepare sodium hydroxide precipitant solution B; prepare complexing agent solution C; prepare doped metal salt solution D;

[0010] Step 2: Add pure water to the reactor and purge with nitrogen for a certain period of time to replace the gas. Heat the reactor to the required temperature and add the solutions B and C prepared in Step 1 into the reactor. Adjust the conditions to the design conditions as the base liquid.

[0011] Step 3: First, add solution A to the prepared base solution to nucleate. During the process, add solution B and solution C to maintain pH and ammonia value within the design range. Control the oxygen content according to the requirements to prepare loose nuclei. After nucleation, introduce dopant D to reduce environmental fluctuations during the nucleation stage and stabilize the process. Adjust the rotation speed according to the growth situation during the process until the target particle size is reached and the reaction stops to obtain a loose porous precursor slurry.

[0012] Step 4: The precursor slurry obtained in Step 3 is subjected to solid-liquid separation, washing, drying and sieving to obtain a multi-component precursor.

[0013] The second technical solution of the present invention is further characterized in that,

[0014] In step 1, the nickel and manganese salts in metal salt solution A are selected from at least one of sulfate, halogen salt, or nitrate; the precipitant B is sodium hydroxide; the complexing agent solution C is ammonia; and the dopant solution D is at least one of ammonium molybdate or sodium molybdate.

[0015] In step 1, the concentration of metal salt solution A is 1.0 mol / L to 3.0 mol / L, the concentration of precipitant sodium hydroxide solution B is 5 mol / L to 15 mol / L, the concentration of complexing agent solution C is 4 mol / L to 14 mol / L, and the concentration of doped metal salt solution D is 1.0 mol / L to 3.0 mol / L.

[0016] In step 2, the amount of pure water added is 1 / 3 to 4 / 5 of the reactor volume, the nitrogen replacement flow rate is 100 ml / min to 500 ml / min, the nitrogen replacement time is 4 h to 10 h, the required temperature inside the reactor is 45 ℃ to 70 ℃, and the design conditions are a pH value of 11.8 to 12.5.

[0017] In step 3, the pH of the reaction is maintained at 11.0 to 12.0, the ammonia concentration is maintained at 0.10 mol / L to 0.40 mol / L, and the stirring rate is 100 rpm to 700 rpm. By introducing nitrogen and air mixed atmosphere into the reaction vessel, micro-oxidation is formed to control the loose structure from the inside out.

[0018] In step 3, the flow rates of both the metal salt solution A and the doped metal solution D are 0.9 L / h to 4.8 L / h.

[0019] In step 3, the metal salt solution A, the precipitant sodium hydroxide solution B, the complexing agent solution C, and the doped metal salt solution D are fed through four channels. The stop particle size is 2.5 μm to 5.0 μm, and the precursor specific surface area is 10 μm. 2 / g~40m 2 / g.

[0020] In step 3, the general chemical formula of the precursor is: Ni x Mn y Mo z (OH)2, 0.5 <x<0.9,0<y<0.5,0<z<0.05,x+z+y=1。

[0021] In step 4, the prepared precursor slurry undergoes solid-liquid separation, washing, drying, and sieving. Solid-liquid separation is performed using a centrifuge. Multiple washings are conducted using hot alkali and hot water at 60–80°C. The concentration of the hot alkali used for washing is 1.0 mol / L to 4.0 mol / L, and the amount of hot water and hot alkali used is 10–20 times that of the precursor material. This continues until the Na content in the material is below 150 ppm and the S content is below 2000 ppm. After washing, the material is dried in an oven at a temperature of 80°C to 120°C until the moisture content is below 1.0 wt%. The material is then sieved and packaged.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention provides a method for preparing a multi-component precursor with a loose porous structure for lithium-ion batteries, which can yield precursor materials with good sphericity and controllable internal structure. This method achieves high specific surface area loose porous precursors through the synergistic control of oxygen content and structure modifiers.

[0024] 2. This invention provides a method for preparing a porous, multi-element precursor for lithium-ion batteries. Through oxygen content control technology, the oxidation degree of the material can be effectively controlled under different manganese contents, resulting in a porous core. Simultaneously, the use of air significantly reduces synthesis costs. Furthermore, by simply controlling the doping amount of molybdenum, a structure modifier, the material's internal porosity can be easily controlled through molybdenum doping's ability to refine primary particles. This improves batch stability and reduces the difficulty of precursor preparation. The porous internal structure of the precursor prepared by this method facilitates more thorough mixing with the lithium source, and the resulting secondary particles exhibit good sphericity and are free of micropowder.

[0025] 3. The loose porous precursor obtained by the preparation method of the loose porous multi-element precursor for lithium-ion batteries of the present invention can effectively release internal stress and suppress the generation of microcracks between secondary grain boundaries. At the same time, molybdenum doping is beneficial to suppress the harmful phase transition that occurs in the long-term cycling process of the cathode material, improve the structural stability of the material, and thus effectively improve the electrochemical performance of the material. Attached Figure Description

[0026] Figure 1 This is a SEM image depicting the external morphology of the precursor obtained in Example 1 of the present invention.

[0027] Figure 2 This is a SEM image depicting the internal morphology of the precursor obtained in Example 1 of this invention.

[0028] Figure 3 This is a SEM image depicting the external morphology of the precursor obtained in Example 2 of the present invention.

[0029] Figure 4 This is a SEM image depicting the internal morphology of the precursor obtained in Example 2 of the present invention.

[0030] Figure 5 This is a SEM image depicting the external morphology of the precursor obtained in Example 3 of the present invention.

[0031] Figure 6 This is a SEM image depicting the internal morphology of the precursor obtained in Example 3 of the present invention.

[0032] Figure 7 This is a SEM image depicting the external morphology of the precursor obtained in Comparative Example 1 of this invention.

[0033] Figure 8 This is a SEM image representing the internal morphology of the precursor obtained in Comparative Example 1 of this invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] like Figures 1-6 As shown, this invention provides a porous, multi-element precursor for lithium-ion batteries, the precursor having the general chemical formula Ni. x Mn y Mo z (OH)₂, of which 0.5 <x<0.9,0<y<0.5,0<z<0.05,x+z+y=1。

[0036] This invention also provides a method for preparing the above-mentioned porous multi-component precursor for lithium-ion batteries, the specific steps of which are as follows:

[0037] Step 1: Prepare nickel and manganese metal salt solution A; prepare sodium hydroxide precipitant solution B; prepare complexing agent solution C; prepare doped metal salt solution D;

[0038] Step 2: Add pure water to the reactor and purge with nitrogen for a certain period of time to replace the gas. Heat the reactor to the required temperature and add the solutions B and C prepared in Step 1 into the reactor. Adjust the conditions to the design conditions as the base liquid.

[0039] Step 3: First, add solution A to the prepared substrate for nucleation. During the process, add solutions B and C to maintain pH and ammonia value within the designed range. Control the oxygen content as needed to prepare loose nuclei. After nucleation, introduce dopant D to reduce environmental fluctuations during the nucleation stage and stabilize the process. Adjust the rotation speed according to the growth situation until the target particle size is reached and the reaction stops to obtain a loose and porous precursor slurry.

[0040] Step 4: The precursor slurry obtained in Step 3 is subjected to solid-liquid separation, washing, drying and sieving to obtain a multi-component precursor.

[0041] In further step 1, the nickel and manganese salts in metal salt solution A are selected from at least one of sulfate, halogen salt, or nitrate; the complexing agent solution C is ammonia; and the dopant solution D is at least one of ammonium molybdate or sodium molybdate.

[0042] In further step 1, the metal salt solution A is preferably used at a concentration of 1.0 mol / L to 3.0 mol / L, the sodium hydroxide precipitant at a concentration of 5 to 15 mol / L, the ammonia solution C at a concentration of 4 to 14 mol / L, and the dopant solution D at a concentration of 1.0 mol / L to 3.0 mol / L.

[0043] In the further step 2, the bottom solution of the reactor is prepared as follows: the amount of pure water added is 1 / 3 to 4 / 5 of the reactor volume, the nitrogen replacement flow rate is 100 to 500 ml / min, the replacement time is 4 to 10 h, the temperature inside the reactor is maintained at 45℃ to 70℃, and the pH of the prepared bottom solution is 11.8 to 12.5.

[0044] In the further step 3, the reaction process maintains the pH at 11.0-12.0, the ammonia concentration at 0.10-0.40 mol / L, and the stirring rate at 100-700 rpm. By introducing a mixed atmosphere of nitrogen and air into the reactor, micro-oxidation is formed, controlling the loose structure from the inside out.

[0045] In the further step 3, the flow rates of the metal salt solution A and the doped metal solution D are both 0.9–4.8 L / h, and the flow rates of the precipitant B and the complexing agent C are adjusted according to the specific requirements of the reaction process.

[0046] In further step 3, solutions A, B, C, and D are fed through four channels to avoid side reactions between the doped metal solutions and the nickel and manganese metal salt solutions. The amount and flow rate of the doped metal solutions are controlled according to the required porosity during the process, and the internal morphology of the precursor is designed. Ultimately, a loose, porous structure can be formed within the material, increasing its specific surface area. The preferred stopping particle size is 2.5–5.0 μm, and the preferred specific surface area of ​​the precursor is 10–40 μm. 2 / g.

[0047] In a further step 3, a method for preparing a loosely porous precursor is obtained, wherein the chemical formula of the doped precursor is: Ni x Mn y Mo z (OH)2, 0.5 <x<0.9,0<y<0.5,0<z<0.05,x+z+y=1。

[0048] In the further step 4, the obtained precursor slurry is subjected to solid-liquid separation, washing, drying, and sieving. Centrifuge is preferred for solid-liquid separation. Multiple washings are performed using hot alkali and hot water at 60-80℃. The concentration of hot alkali used for washing is 1.0-4.0 mol / L, and the amount of hot water and hot alkali used is 10-20 times that of the precursor material, until the Na content of impurities in the material is lower than 150 ppm and the S content of impurities is lower than 2000 ppm. After washing, the material is dried in an oven at a temperature of 80-120℃ until the moisture content is lower than 1.0 wt%, and then screened and packaged.

[0049] Compared to existing technologies, this invention effectively improves the porosity of the material from the inside out by controlling the degree of oxidation in the early stage, adjusting the morphology of primary particles, and preparing a disordered and porous core, while also optimizing the sphericity of the precursor. Secondly, by controlling the introduction of molybdenum, the radius region of the porous structure can be controlled. By controlling the amount added, the morphology of the primary particles and the porosity of the porous structure of the precursor can be effectively controlled, increasing the surface area of ​​the precursor material, improving the contact area during lithium mixing, and resulting in more uniform mixing. This porous precursor morphology can effectively regulate the morphology of the sintered cathode material, helping to reduce stress accumulation, alleviate the epitaxial growth of microcracks during cathode material cycling, and stabilize the material structure. Simultaneously, Mo… 6+ Replacing Ni sites to increase interlayer spacing can effectively improve the diffusion rate of lithium ions and the rate performance of the battery. This loose porous structure solves the problems caused by uneven lithium mixing, high residual lithium, difficulty in lithium ion intercalation / deintercalation after sintering, and incomplete capacity utilization due to the dense accumulation of primary particles with prolonged reaction time in conventional processes. By linking bulk doping and oxidation processes to adjust the morphology of primary particles inside the precursor, the uniformity of the internal structure of the material is improved. This preparation method is simple, easy to operate, and convenient for subsequent industrialization.

[0050] To better demonstrate the features of the present invention, the following detailed description is provided in conjunction with embodiments:

[0051] Example 1

[0052] Step 1, prepare the reaction solution: Weigh out nickel sulfate and manganese sulfate metal salts and mix them in a stoichiometric ratio of 70:30, with a total metal solution concentration of 2 mol / L; prepare a sodium hydroxide precipitant solution with a concentration of 10 mol / L; prepare an ammonia solution with a concentration of 7 mol / L as a complexing agent.

[0053] Step 2, preparing the base solution: Add 1 / 3 of the volume of purified water to a 50L reactor as needed, purge with nitrogen at 500ml / min until the oxygen content in the reactor is below 0.5%, and heat to 45℃. Then, adjust the pH of the base solution to 12.00 by adding sodium hydroxide, and adjust the concentration of the complexing agent ammonia to 0.15mol / L as the nucleation condition, using a rotation speed of 600rpm.

[0054] Step 3, Precipitation Reaction: A metal salt solution is initially introduced into the prepared base solution at a flow rate of 0.9 L / h for 20 min to allow nucleation. During this process, sodium hydroxide (a precipitant) and ammonia (a complexing agent) are introduced as regulators. The nucleation pH and ammonia value are maintained within the aforementioned range. After nucleation, the pH is slowly lowered to 11.50–11.70, and the pH is maintained at 11.00–11.20 throughout the subsequent reaction. The ammonia concentration is stabilized at 0.10–0.20 mol / L to create a suitable growth environment. From the start of feeding, 5.0%–10% oxygen is introduced into the reactor to inhibit primary particle aggregation. The reaction temperature is maintained at 45℃ throughout the process. The stirring speed is adjusted according to the growth progress, with each adjustment not exceeding 80 rpm. Once the reactor environment and growth conditions stabilize, the salt flow rate is increased to 4.8 L / h, and feeding is stopped when the particle size reaches 2.5–3.0 μm. The reaction is then terminated. The final synthesized material has the chemical formula: Ni. 0.7 Mn 0.3 (OH)2.

[0055] Step 4: The synthesized material is subjected to solid-liquid separation using a centrifuge. It is then washed multiple times with hot alkali at 80℃ and a concentration of 4mol / L and hot water at 50℃ until the Na content of impurities in the material is less than 150ppm and the S content of impurities is less than 2000ppm. After washing, it is placed in a 110℃ oven for 24 hours to remove moisture until the moisture content is less than 1.0wt%. The material is then sieved and bagged to obtain the finished ternary precursor material.

[0056] The precursor product was tested and found to have a particle size D50 of 3.104 μm and a specific surface area of ​​11.619 m². 2 / g, morphological characterization image (SEM) is shown in the example. Figure 1 and Figure 2 As shown in the figure, the secondary particles of the precursor have good sphericity, the outer surface of the secondary particle profile is radially distributed, the core is randomly and loosely arranged, the primary particles are medium laths, and the density is reduced due to accumulation.

[0057] Example 2

[0058] Step 1, Prepare the reaction solution: Weigh nickel sulfate, manganese sulfate and ammonium molybdate metal salts in a stoichiometric ratio of 60:38:2, dissolve the nickel sulfate, cobalt sulfate and manganese sulfate metal salts together to a total concentration of 1 mol / L, prepare an ammonium molybdate solution with a concentration of 4 mol / L according to the properties of the doping elements, and feed it separately; prepare a sodium hydroxide precipitant solution with a concentration of 5 mol / L; prepare an ammonia solution with a concentration of 4 mol / L as a complexing agent.

[0059] Step 2, preparing the base solution: Add 1 / 2 full of purified water to a 50L reactor as needed, purge with nitrogen at 300ml / min until the oxygen content in the reactor is below 0.5%, and heat to 60℃. Then, adjust the pH of the base solution to 12.30 by adding sodium hydroxide, and adjust the concentration of the complexing agent ammonia to 0.25mol / L as the nucleation condition, using a rotation speed of 700rpm.

[0060] Step 3, Precipitation reaction: A metal salt solution is introduced into the prepared base solution at an initial flow rate of 1.2 L / h for 30 min for nucleation. During this process, sodium hydroxide (a precipitant) and ammonia (a complexing agent) are introduced as regulators. The nucleation pH and ammonia value are kept within the above range. After nucleation, a dopant solution is introduced at an initial flow rate of 0.3 L / h, and the pH is slowly reduced to 11.60–11.70. Throughout the subsequent reaction process, the pH in the reactor is maintained at 11.60–11.70, and the ammonia concentration is kept stable at 0.20–0.30 mol / L as the growth environment. From the beginning of feeding, 5.0%–10% oxygen is introduced into the reactor to form a loose nucleus and to inhibit the dense packing of primary particles. The reaction temperature inside the reactor was maintained at 60℃ throughout the process. The stirring speed was adjusted downwards according to the growth, with each adjustment not exceeding 80 rpm. After the reactor environment and growth conditions stabilized, the salt flow rate was increased to 4.8 L / h. Feeding was stopped when the particle size reached 3.8–4.2 μm, and the reaction was terminated. The final synthesized material has the chemical formula: Ni. 0.60 Mn 0.38 Mo 0.02 (OH)2.

[0061] Step 4: The synthesized material is subjected to solid-liquid separation using a centrifuge. It is then washed multiple times with hot alkali at 70℃ and a concentration of 2.5mol / L and hot water at 60℃ until the Na content of the impurity in the material is less than 150ppm and the S content of the impurity is less than 2000ppm. After washing, it is placed in a 100℃ oven for 24 hours to remove the moisture until the moisture content is less than 1.0wt%. The material is then sieved and bagged to obtain the finished multi-component precursor material.

[0062] The precursor product was tested and found to have a particle size D50 of 4.054 μm and a specific surface area of ​​20.852 m². 2 / g, morphological characterization image (SEM) is shown in the example. Figure 3 and Figure 4 As shown in the figure, the secondary particles of the precursor have good sphericity, and the outer surface of the secondary particle cross-section is radially distributed. The core is randomly and loosely arranged, while the primary particles are short needle-shaped and loosely packed.

[0063] Example 3

[0064] Step 1, Prepare the reaction solution: Weigh nickel sulfate, manganese sulfate and ammonium molybdate metal salts in a stoichiometric ratio of 65:30:5. Dissolve the nickel sulfate, cobalt sulfate and manganese sulfate metal salts together to a total concentration of 3 mol / L. Prepare an ammonium molybdate solution with a concentration of 6 mol / L and feed it separately according to the properties of the doping elements. Prepare a sodium hydroxide precipitant solution with a concentration of 15 mol / L. Prepare an ammonia solution with a concentration of 12 mol / L as a complexing agent.

[0065] Step 2, Preparing the base solution: Add 3 / 5 of the volume of purified water to a 50L reactor as needed, purge with nitrogen at 200ml / min until the oxygen content in the reactor is below 0.5%, and heat to 70℃. Then, adjust the pH of the base solution to 12.50 by adding sodium hydroxide, and adjust the concentration of the complexing agent ammonia to 0.35mol / L as the nucleation condition, using a rotation speed of 650rpm.

[0066] Step 3, Precipitation reaction: A metal salt solution is introduced into the prepared base solution at an initial flow rate of 1.2 L / h for 30 min for nucleation. During this process, sodium hydroxide as a precipitant and ammonia as a complexing agent are introduced as regulators. The nucleation pH and ammonia value are kept within the above range. After nucleation, a dopant solution is introduced at an initial flow rate of 0.6 L / h, and the pH is slowly reduced to 11.90–12.00. Throughout the subsequent reaction process, the pH in the reactor is maintained at 11.90–12.00, and the ammonia concentration is kept stable at 0.35–0.40 mol / L as the growth environment. From the beginning of feeding, 5.0%–10% oxygen is introduced into the reactor to form a loose nucleus and to inhibit the dense accumulation of primary particles. The reaction temperature inside the reactor was maintained at 70℃ throughout the process. The stirring speed was adjusted downwards according to the growth, with each adjustment not exceeding 80 rpm. After the reactor environment and growth conditions stabilized, the salt flow rate was increased to 4.8 L / h. Feeding was stopped when the particle size reached 4.5–5.0 μm, and the reaction was terminated. The final synthesized material has the chemical formula: Ni. 0.65 Mn 0.30 Mo 0.05 (OH)2.

[0067] Step 4: The synthesized material is subjected to solid-liquid separation using a centrifuge. It is then washed multiple times with hot alkali at 70℃ and a concentration of 1mol / L and hot water at 60℃ until the Na content of the impurity in the material is less than 150ppm and the S content of the impurity is less than 2000ppm. After washing, it is placed in an 80℃ oven for 48 hours to remove the moisture until the moisture content is less than 1.0wt%. The material is then sieved and bagged to obtain the finished multi-component precursor material.

[0068] The precursor product was tested and found to have a particle size D50 of 4.854 μm and a specific surface area of ​​35.233 m². 2 / g, morphological characterization image (SEM) is shown in the example. Figure 5 and Figure 6As shown in the figure, the secondary particles of the precursor have good sphericity, the outer surface of the secondary particle cross-section is radially distributed, the core is randomly and loosely arranged, and the primary particles are thin-plate-like and loosely packed.

[0069] Comparative Example 1

[0070] Step 1, prepare the reaction solution: Weigh out nickel sulfate and manganese sulfate metal salts and mix them in a stoichiometric ratio of 80:20, with a total metal solution concentration of 1.5 mol / L; prepare a sodium hydroxide precipitant solution with a concentration of 12 mol / L; and prepare an ammonia solution with a concentration of 15 mol / L as a complexing agent.

[0071] Step 2, preparing the base solution: Add 4 / 5 of the volume of purified water to a 50L reactor as needed, purge with nitrogen at 200ml / min until the oxygen content in the reactor is below 0.5%, and heat to 50℃. Then, adjust the pH of the base solution to 11.80 by adding sodium hydroxide, and adjust the concentration of the complexing agent ammonia to 0.1mol / L as the nucleation condition, using a rotation speed of 700rpm.

[0072] Step 3, Precipitation Reaction: A metal salt solution is initially introduced into the prepared base solution at a flow rate of 1.2 L / h for 40 min for nucleation. During this process, sodium hydroxide (a precipitant) and ammonia (a complexing agent) are introduced as regulators. The nucleation pH and ammonia value are maintained within the aforementioned range. After nucleation, the pH is slowly decreased to 11.50–11.70, and the pH is maintained at 11.50–11.60 throughout the subsequent reaction. The ammonia concentration is kept stable at 0.20 mol / L as the growth environment. Nitrogen gas is introduced at a rate of 200 ml / min for gas replacement throughout the process to ensure that no other gases interfere with the primary particle morphology. The reaction temperature is maintained at 50℃ throughout the process. The stirring speed is adjusted according to the growth, with each adjustment not exceeding 80 rpm. After the environment and growth conditions stabilize, the salt flow rate is increased to 4.8 L / h. Feeding is stopped when the particle size reaches 3.0–4.0 μm, and the reaction is terminated. The final synthesized material has the chemical formula: Ni. 0.80 Mn 0.20 (OH)2.

[0073] Step 4: The synthesized material is subjected to solid-liquid separation using a centrifuge. It is then washed multiple times with hot alkali at 60℃ and a concentration of 2.5mol / L and hot water at 60℃ until the Na content of impurities in the material is less than 150ppm and the S content of impurities is less than 2000ppm. After washing, it is placed in a 120℃ oven for 24 hours to remove moisture until the moisture content is less than 1.0wt%. The material is then sieved and bagged to obtain the finished ternary precursor material.

[0074] The precursor product was tested and found to have a particle size D50 of 3.856 μm and a specific surface area of ​​5.314 m². 2 / g, morphological characterization image (SEM) is shown in the example. Figure 7 and Figure 8 As shown in the figure, the precursors are obviously aggregated and mostly twinned, with poor sphericity. The actual particle size is smaller than the required particle size. The secondary particles are compact inside and have a radial distribution. The primary particles are densely packed in thick strips.

Claims

1. A method for preparing a loose, porous, multi-component precursor, wherein the precursor has the general chemical formula Ni. x Mn y Mo z (OH)2, where, 0.5 < x < 0.9, 0 < y < 0.5, 0 < z < 0.05, x + z + y = 1, and it is characterized in that it includes the following steps: Step 1, configure the metal salt solution A of nickel and manganese; prepare the precipitant sodium hydroxide solution B; prepare the complexing agent solution C; configure the doping metal salt solution D; Step 2, add pure water into the reaction kettle and introduce nitrogen for replacement for a certain period of time, heat up to the required temperature, and add the solution B and solution C configured in Step 1 into the reaction kettle, and adjust to the designed conditions as the bottom liquid; Step 3, first add the solution A into the adjusted bottom liquid for nucleation. During the process, add the solution B and solution C to maintain the pH and ammonia value within the designed range, control the oxygen content according to the requirements to prepare a loose inner core. After the nucleation is completed, introduce the dopant D to reduce the environmental fluctuation in the nucleation stage and stabilize the process. During the process, adjust the rotation speed according to the growth situation until the target particle size is reached and the reaction is stopped to obtain a loose porous precursor slurry; In the said Step 3, the pH during the reaction process is maintained at 11.0 - 12.0, the ammonia concentration is maintained at 0.10 mol / L - 0.40 mol / L, the stirring rate is 100 rpm - 700 rpm, and a micro-oxidation is formed by transporting a mixed atmosphere of nitrogen and air into the reaction kettle to control the loose structure from the inside to the outside; Step 4, perform solid-liquid separation, washing, drying and sieving on the precursor slurry prepared in Step 3 to obtain a multi-component precursor.

2. The method for preparing a porous, multi-element precursor according to claim 1, characterized in that, In the said Step 1, the nickel and manganese salts of the metal salt solution A are selected from at least one of sulfates, halide salts or nitrates, the precipitant B is sodium hydroxide, the complexing agent solution C is ammonia water, and the dopant solution D is at least one of ammonium molybdate or sodium molybdate.

3. The method for preparing a loose, porous, multi-component precursor according to claim 1, characterized in that, In the said Step 1, the concentration of the metal salt solution A is 1.0 mol / L - 3.0 mol / L, the concentration of the precipitant sodium hydroxide solution B is 5 mol / L - 15 mol / L, the concentration of the complexing agent solution C is 4 mol / L - 14 mol / L, and the concentration of the doping metal salt solution D is 1.0 mol / L - 3.0 mol / L.

4. The method for preparing a loose, porous, multi-component precursor according to claim 1, characterized in that, In the said Step 2, the addition amount of pure water is 1 / 3 - 4 / 5 of the volume of the reaction kettle, the nitrogen replacement flow rate is 100 ml / min - 500 ml / min, the nitrogen replacement time is 4 h - 10 h, the required temperature in the reaction kettle is 45°C - 70°C, and the designed condition is that the pH value is 11.8 - 12.

5.

5. The method for preparing a loose, porous, multi-component precursor according to claim 1, characterized in that, In the said Step 3, the flow rates of both the metal salt solution A and the doping metal solution D used are 0.9 L / h - 4.8 L / h.

6. The method for preparing a porous, multi-component precursor according to claim 5, characterized in that, In step 3, the metal salt solution A, the precipitant sodium hydroxide solution B, the complexing agent solution C, and the doped metal salt solution D are fed through four channels. The stop particle size is 2.5 μm to 5.0 μm, and the precursor specific surface area is 10 μm. 2 / g ~40m 2 / g.

7. The method for preparing a porous, multi-component precursor according to claim 6, characterized in that, In step 3, the general chemical formula of the precursor is: Ni x Mn y Mo z (OH)2, 0.5 <x<0.9,0<y<0.5,0<z<0.05,x+z+y=1。 8. The method for preparing a loose, porous, multi-component precursor according to claim 1, characterized in that, In the said Step 4, perform solid-liquid separation, washing, drying and sieving on the prepared precursor slurry. The solid-liquid separation is carried out by a centrifuge, and it is washed multiple times with hot alkali and hot water at 60 - 80°C. The concentration of the hot alkali used for washing is 1.0 mol / L - 4.0 mol / L, and the usage amounts of the hot water and hot alkali are 10 - 20 times that of the precursor material until the content of impurity Na in the material is lower than 150 ppm and the content of impurity S is lower than 2000 ppm. After the washing is completed, select an oven drying temperature of 80°C - 120°C for drying, and perform sieving and packaging when the moisture content is lower than 1.0 wt%.

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