Method for preparing multi-element positive electrode material precursor through composite oxidation regulation and control

Abstract

The invention provides a method for preparing a multi-element positive electrode material precursor through composite oxidation regulation and control. The method comprises the following steps: an initial growth stage: a conventional growth process is adopted in the early stage, and requirements can be met only by adjusting conventional parameters; in the composite oxidation growth stage, an H2O2-O3 synergistic oxidation mechanism is innovatively adopted, and the generation of submicron small particles can be inhibited by strictly controlling the content of free nickel and the content of dissolved oxygen in the growth process; and finally, in the aging stage, a small amount of citric acid is added to further stabilize the growth system and repair the surface appearance of the final precursor, so that the target requirement is met. According to the preparation method, through a composite oxidation process, the occurrence of submicron small particles in the later growth stage can be greatly reduced; compared with the traditional process, the precursor and the corresponding positive electrode material prepared by the method have the advantages of narrower particle size distribution, higher cycle performance and longer service life, and can meet the requirements of high-energy density batteries.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of modification of nickel-based layered multi-element positive electrode materials, in particular to a method for preparing a multi-element positive electrode material precursor by composite oxidation regulation. BACKGROUND

[0002] As a key determinant of the energy density (>=200 mAh / g) and cycle life (>=1000 times) of lithium ion batteries, high-nickel ternary positive electrode materials (NCM / NCA) occupy a dominant position in the power battery market, and their cost accounts for 30%-60% of the total cost of the battery. The particle size distribution, tap density and surface integrity of the precursor, which is the structural matrix of the positive electrode material, directly determine the boundaries of battery performance.

[0003] In the preparation process of the traditional co-precipitation method, submicron-sized small particle byproducts are easily produced in the later stage of the reaction. These small particles will abnormally agglomerate during the high-temperature sintering stage, resulting in a wide particle size distribution of the final positive electrode material, significantly reducing the tap density and electrode compaction density. More seriously, fine powder particles will exacerbate the electrolyte side reaction during the battery charging and discharging process, causing an increase in gas production and accelerated capacity decay. In addition, although the oxidation technology (such as CN115872367A) can effectively reduce the concentration of free nickel ions, its strong oxidation impact mode (O3+pH sudden drop) will damage the surface morphology integrity of the precursor. More seriously, the sharp fluctuation of pH will cause local supersaturation nucleation, which will increase the proportion of fine powder.

[0004] Therefore, there is an urgent need to develop a new precursor process that can synergistically optimize particle size control and surface integrity, inhibit the generation of small particles, and repair the surface morphology, providing a material basis for high-energy-density lithium batteries. SUMMARY

[0005] The purpose of the present application is to provide a method for preparing a multi-element positive electrode material precursor by composite oxidation regulation to solve the problems raised in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a method for preparing a multi-element positive electrode material precursor by composite oxidation regulation, characterized by comprising the following steps:

[0007] Step S1: inert gas, multi-element nickel-based sulfate solution, NaOH solution and nitrogen-containing complexing agent are simultaneously introduced into a reaction kettle containing pure water, NaOH and nitrogen-containing complexing agent, and the pH value is maintained at 12.0-13.5, the concentration of the nitrogen-containing complexing agent is 0.5-1.5 mol / L, the stirring line speed is 9-12 m / s, the solution temperature is 35-80℃, the free nickel ion concentration is <=50 ppm, and the dissolved oxygen content is <0.01 mg / L, until the slurry D 50Reach 2.0-5.0 μm; then continuously decrease the pH to 11.0-12.0, and increase the stirring speed to 7-9 m / s until the slurry D... 50 Reaching 5.0-7.0μm;

[0008] Step S2: Continuously introduce a multi-component nickel-based sulfate solution, NaOH solution, nitrogen-containing complexing agent, and H2O2 solution into step S1. Adjust the nitrogen-containing complexing agent concentration to 0.1-0.5 mol / L, the stirring linear speed to 4-7 m / s, the solution temperature to 35-80℃, the pH value to 10.0-11.0, the free nickel ion concentration to ≤30 ppm, and the dissolved oxygen content to 6.0-7.5 mg / L. When the free nickel ion concentration is >30 ppm, introduce O3 until slurry D... 50 Feeding is stopped once the particle size reaches 7.0-12.0 μm.

[0009] Step S3: Inert gas is continuously introduced into the slurry from step S2. The solution temperature is 50-60℃ and the stirring speed is 3-5m / s until the dissolved oxygen content is ≤1.0mg / L. Citric acid is then introduced for 10-30min, followed by aging and stirring for 30-200min. After washing and drying, the precursor of the multi-element cathode material is obtained.

[0010] Preferably, the nitrogen-containing complexing agent is one or a combination of several selected from ammonia, ammonium sulfite, ammonium bisulfite, ammonium bisulfate, ammonium sulfide, ammonium hydrosulfide, ammonium thiosulfate, or ammonium carbonate; the inert gas is one or a combination of several selected from nitrogen and argon.

[0011] Preferably, the multi-element nickel-based sulfate is XSO4, wherein X must contain Ni, and the other elements are one or more of Co, Mn, Al, Mg, Ti, and Sr; the molar concentration of the XSO4 solution is 1.0-3.0 mol / L, the molar concentration of the NaOH solution is 2.0-15.0 mol / L, and the molar concentration of the nitrogen-containing complexing agent is 5.0-15.0 mol / L.

[0012] Preferably, the amount of H2O2 solution added is 0.01-0.2wt%, the amount of O3 introduced is 50-150ppm per time, the time of each time is 30-180s, and the interval between times is 5-10min; the concentration of citric acid is 0.005-0.02mol / L.

[0013] Preferably, the multi-element cathode material precursor is calcined after being uniformly mixed with a lithium-containing compound, wherein the lithium-containing compound is one or a combination of lithium hydroxide, lithium carbonate, lithium acetate, or lithium nitrate.

[0014] Preferably, the calcination step is as follows: heating to 400-600℃ at a rate of 3-5℃ / min, holding at that temperature for 3-8 hours, and then heating to 700-900℃ at a rate of 2-5℃ / min, holding at that temperature for 10-15 hours.

[0015] Beneficial effects:

[0016] (1) This invention significantly reduces the problem of submicron-sized particles appearing in the later stage of growth: by adjusting the amount of H2O2-O3 synergistic oxidation through real-time feedback of dissolved oxygen, secondary nucleation is suppressed, thereby greatly reducing the occurrence of small particles.

[0017] (2) The present invention can improve batch consistency: by reducing the occurrence of small particles through composite oxidation process, the uniform distribution of particle size is improved, and the consistency required for industrial production is improved.

[0018] (3) In the aging stage, the present invention further stabilizes the growth system and repairs the surface morphology of the final precursor by adding a small amount of citric acid to achieve the target requirements.

[0019] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more apparent and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0020] Figure 1 SEM image of the multi-component cathode material precursor prepared in this invention;

[0021] Figure 2 SEM image of the precursor of the multi-component cathode material in Comparative Example 1;

[0022] Figure 3 The image shows the SEM image of the precursor of the multi-element cathode material in Comparative Example 2. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0026] Example 1

[0027] This invention discloses a method for preparing a multi-component cathode material precursor through composite oxidation regulation, comprising the following steps:

[0028] Step S1: Nitrogen gas, 2.0 mol / L XSO4 (M = Ni, Co, Mn, where the molar ratio of Ni:Co:Mn is 0.90:0.05:0.05), 10.0 mol / L NaOH solution, and 10.0 mol / L ammonia water are simultaneously introduced into a reactor containing pure water, NaOH, and a nitrogen-containing complexing agent. The pH is maintained at 13.5, the ammonia concentration at 1.5 mol / L, the stirring speed at 12 m / s, the solution temperature at 70℃, the free nickel ion concentration at ≤50 ppm, and the dissolved oxygen content at <0.01 mg / L, until slurry D is obtained. 50 Reaching 5.0 μm; then continuously decreasing the pH to 12.0, and increasing the stirring speed to 9 m / s, until the slurry D... 50 Reaching 7.0μm;

[0029] Step S2: Continuously introduce 2.0 mol / L XSO4 (M = Ni, Co, Mn, where the molar ratio of Ni:Co:Mn is 0.90:0.05:0.05), 10.0 mol / L NaOH solution, 10.0 mol / L ammonia water, and H2O2 solution into step S1. The amount of H2O2 solution added is 0.2 wt%. Adjust the ammonia water concentration to 0.5 mol / L, the stirring linear speed to 7 m / s, the solution temperature to 70℃, the pH value to 11.0, the free nickel ion concentration to ≤30 ppm, and the dissolved oxygen content to 7.5 mg / L. When the free nickel ion concentration is >30 ppm, introduce O3 at a rate of 150 ppm per introduction for 180 s, with an interval of 5 min between introductions, until slurry D... 50 Feeding was stopped after the particle size reached 12.0 μm.

[0030] Step S3: Nitrogen gas is continuously introduced into the slurry from Step S2. The solution temperature is 60℃, and the stirring speed is 5m / s until the dissolved oxygen content is ≤1.0mg / L. Then, 0.02mol / L citric acid is introduced for 30min, followed by aging and stirring for 200min. After washing and drying, the precursor of the multi-element cathode material is obtained. Figure 1 As shown, the large-particle precursor prepared by the process used in this patent has good sphericity and few small particles, which can improve the performance of the cathode material after subsequent sintering.

[0031] The precursor from step 3) was mixed evenly with LiOH·H2O, and then placed in a tube furnace. The temperature was increased to 600°C at a rate of 5°C / min and held for 8 hours. Then the temperature was increased to 900°C at a rate of 5°C / min and held for 15 hours to obtain the corresponding cathode material.

[0032] The cathode material prepared above was washed with water and modified by coating to prepare electrode sheets, which were then assembled into CR2032 coin cells. The electrochemical performance was tested, and the initial coulombic efficiency was 94.6%, the 0.1C cycle capacity was as high as 222.5 mAh / g, and the capacity retention rate was as high as 97.9% after 100 cycles at 0.1C.

[0033] Example 2

[0034] This invention discloses a method for preparing a multi-component cathode material precursor through composite oxidation regulation, comprising the following steps:

[0035] Step S1: Nitrogen gas, 1.5 mol / L XSO4 (M = Ni, Co, Mn, Al, where the molar ratio of Ni:Co:Mn:Al is 0.94:0.02:0.03:0.01), 8.0 mol / L NaOH solution, and 8.0 mol / L ammonia water are simultaneously introduced into a reactor containing pure water, NaOH, and a nitrogen-containing complexing agent. The pH is maintained at 13.0, the ammonia concentration at 1.0 mol / L, the stirring speed at 10 m / s, the solution temperature at 60℃, the free nickel ion concentration at ≤50 ppm, and the dissolved oxygen content at <0.01 mg / L, until slurry D is obtained. 50 Reaching 4.0 μm; then continuously decreasing the pH to 11.5, and increasing the stirring speed to 8 m / s, until the slurry D... 50 Reaching 6.0μm;

[0036] Step S2: Continuously introduce 1.5 mol / L XSO4 (M = Ni, Co, Mn, Al, where the molar ratio of Ni:Co:Mn:Al is 0.94:0.02:0.03:0.01), 8.0 mol / L NaOH solution, 8.0 mol / L ammonia solution, and H2O2 solution into step S1. The amount of H2O2 solution added is 0.1 wt%. Adjust the ammonia concentration to 0.3 mol / L, the stirring linear speed to 6 m / s, the solution temperature to 60℃, the pH value to 10.5, the free nickel ion concentration to ≤30 ppm, and the dissolved oxygen content to 7.0 mg / L. When the free nickel ion concentration is >30 ppm, introduce O3 at a rate of 100 ppm per introduction for 150 s, with an interval of 8 min between introductions, until slurry D... 50 Feeding was stopped after the particle size reached 11.0 μm.

[0037] Step S3: Nitrogen gas is continuously introduced into the slurry from step S2 at a solution temperature of 55°C and a stirring speed of 4 m / s until the dissolved oxygen content is ≤1.0 mg / L. Then, 0.01 mol / L citric acid is introduced for 20 min, followed by aging and stirring for 150 min. After washing and drying, the precursor of the multi-element cathode material is obtained.

[0038] The precursor from step 3) was mixed evenly with LiOH·H2O, and then placed in a tube furnace. The temperature was increased to 500°C at a rate of 4°C / min and held for 7 hours. Then the temperature was increased to 800°C at a rate of 4°C / min and held for 12 hours to obtain the corresponding cathode material.

[0039] The cathode material prepared above was washed with water and modified by coating to prepare electrode sheets, which were then assembled into CR2032 coin cells. The electrochemical performance was tested, and the initial coulombic efficiency was 93.3%, the 0.1C cycle capacity was as high as 231.2 mAh / g, and the capacity retention rate was as high as 97.5% after 100 cycles at 0.1C.

[0040] Example 3

[0041] This invention discloses a method for preparing a multi-component cathode material precursor through composite oxidation regulation, comprising the following steps:

[0042] Step S1: Nitrogen gas, 1.2 mol / L XSO4 (M = Ni, Mn, Al, Mg, where the molar ratio of Ni:Mn:Al:Mg is 0.96:0.02:0.01:0.01), 6.0 mol / L NaOH solution, and 7.0 mol / L ammonia water are simultaneously introduced into a reactor containing pure water, NaOH, and a nitrogen-containing complexing agent. The pH is maintained at 12.5, the ammonia concentration at 0.6 mol / L, the stirring speed at 9.5 m / s, the solution temperature at 50℃, the free nickel ion concentration at ≤50 ppm, and the dissolved oxygen content at <0.01 mg / L, until slurry D is obtained. 50 Reaching 3.0 μm; then continuously decreasing the pH to 11.1, and the stirring linear velocity to 7.1 m / s, until slurry D... 50 Reaching 5.5μm;

[0043] Step S2: Continuously introduce 1.2 mol / L XSO4 (M = Ni, Mn, Al, Mg, where the molar ratio of Ni:Mn:Al:Mg is 0.96:0.02:0.01:0.01), 6.0 mol / L NaOH solution, 7.0 mol / L ammonia solution, and H2O2 solution into step S1. The amount of H2O2 solution added is 0.05 wt%. Adjust the ammonia concentration to 0.1 mol / L, the stirring linear speed to 5 m / s, the solution temperature to 50℃, the pH value to 10.1, the free nickel ion concentration to ≤30 ppm, and the dissolved oxygen content to 6.0 mg / L. When the free nickel ion concentration is >30 ppm, introduce O3 at a rate of 80 ppm per introduction for 120 s, with an interval of 10 min, until slurry D... 50 Feeding is stopped once the particle size reaches 10.0 μm.

[0044] Step S3: Nitrogen gas is continuously introduced into the slurry from step S2. The solution temperature is 50℃ and the stirring linear speed is 3.5m / s until the dissolved oxygen content is ≤1.0mg / L. Then, 0.005mol / L citric acid is introduced for 10min. After aging and stirring for 100min, the precursor of the multi-element cathode material is obtained after washing and drying.

[0045] The precursor from step 3) was mixed evenly with LiOH·H2O, and then placed in a tube furnace. The temperature was increased to 400°C at a rate of 3°C / min and held for 6 hours. The temperature was then increased to 700°C at a rate of 3°C / min and held for 10 hours to obtain the corresponding cathode material.

[0046] The cathode material prepared above was washed with water and modified by coating to prepare electrode sheets, which were then assembled into CR2032 coin cells. The electrochemical performance was tested, and the initial coulombic efficiency was 94.1%, the 0.1C cycle capacity was as high as 238.2 mAh / g, and the capacity retention rate was as high as 98.4% after 100 cycles at 0.1C.

[0047] Comparative Example 1

[0048] Step S1: Nitrogen gas, 2.0 mol / L XSO4 (M = Ni, Co, Mn, where the molar ratio of Ni:Co:Mn is 0.90:0.05:0.05), 10.0 mol / L NaOH solution, and 10.0 mol / L ammonia water are simultaneously introduced into a reactor containing pure water, NaOH, and a nitrogen-containing complexing agent. The pH is maintained at 13.5, the ammonia concentration at 1.5 mol / L, the stirring speed at 12 m / s, the solution temperature at 70℃, the free nickel ion concentration at ≤50 ppm, and the dissolved oxygen content at <0.01 mg / L, until slurry D is obtained. 50 Reaching 5.0 μm; then continuously decreasing the pH to 12.0, and increasing the stirring speed to 9 m / s, until the slurry D... 50 Reaching 7.0μm;

[0049] Step S2: Continuously introduce 2.0 mol / L XSO4 (M = Ni, Co, Mn, where the molar ratio of Ni:Co:Mn is 0.90:0.05:0.05), 10.0 mol / L NaOH solution, and 10.0 mol / L ammonia solution into step S1, adjusting the ammonia concentration to 0.5 mol / L, the stirring linear speed to 7 m / s, the solution temperature to 70℃, and the pH value to 11.0; until slurry D... 50 The feed was stopped after reaching a thickness of 12.0 μm; after washing and drying, a multi-element cathode material precursor was obtained. Figure 2 As shown, the precursor prepared by traditional processes has surface cracks and many small particles, which will also reduce the performance of the cathode material after subsequent sintering.

[0050] The precursor from step 2) was mixed evenly with LiOH·H2O, and then placed in a tube furnace. The temperature was increased to 600°C at a rate of 5°C / min and held for 8 hours. Then the temperature was increased to 900°C at a rate of 5°C / min and held for 15 hours to obtain the corresponding cathode material.

[0051] After the above-prepared cathode material was washed with water and modified by coating, an electrode sheet was prepared and assembled into a CR2032 coin cell. The electrochemical performance was tested, and its initial coulombic efficiency was only 80.8%, the 0.1C cycle capacity was only 200.2 mAh / g, and after 100 cycles at 0.1C, the capacity retention rate was only 81.6%.

[0052] Comparative Example 2

[0053] Step S1: Nitrogen gas, 2.0 mol / L XSO4 (M = Ni, Co, Mn, where the molar ratio of Ni:Co:Mn is 0.90:0.05:0.05), 10.0 mol / L NaOH solution, 10.0 mol / L ammonia water, and O3 are simultaneously introduced into a reactor containing pure water, NaOH, and a nitrogen-containing complexing agent. The O3 concentration is maintained at 150 ppm, pH value at 13.5, ammonia water concentration at 1.5 mol / L, stirring speed at 12 m / s, solution temperature at 70℃, free nickel ion concentration ≤50 ppm, and dissolved oxygen content <0.01 mg / L until the slurry D50 reaches 5.0 μm. Then, the pH value is continuously reduced to 12.0, and the stirring speed is increased to 9 m / s until the slurry D50 reaches 7.0 μm.

[0054] Step S2: Continuously introduce 2.0 mol / L XSO4 (M = Ni, Co, Mn, where the molar ratio of Ni:Co:Mn is 0.90:0.05:0.05), 10.0 mol / L NaOH solution, and 10.0 mol / L ammonia solution into step S1. Adjust the ammonia concentration to 0.5 mol / L, the stirring linear speed to 7 m / s, and O3 to maintain an O3 concentration of 150 ppm. Keep the solution temperature at 70℃ and the pH value at 12.0. Slurry D 50 When the slurry reaches a particle size of 10.0 μm, 1.0 mol / L dilute sulfuric acid is added. After 10 minutes, the pH value drops sharply to 11.0. The addition of dilute sulfuric acid is then stopped, and the pH value is maintained at 11.0 until slurry D... 50 Feeding was stopped when the particle size reached 12.0 μm. After washing and drying, a multi-element cathode material precursor was obtained. Figure 3 As shown, the precursor prepared by the process of rapidly decreasing pH with O3 also has problems such as cracks and small particles on the surface, which will also reduce the performance of the cathode material after subsequent sintering.

[0055] The precursor from step 2) was mixed evenly with LiOH·H2O, and then placed in a tube furnace. The temperature was increased to 600°C at a rate of 5°C / min and held for 8 hours. Then the temperature was increased to 900°C at a rate of 5°C / min and held for 15 hours to obtain the corresponding cathode material.

[0056] After washing and coating modification, the cathode material prepared above was used to prepare electrode sheets, which were then assembled into CR2032 coin cells. The electrochemical performance was tested, and the initial coulombic efficiency was only 86.7%, the 0.1C cycle capacity was only 203.7 mAh / g, and the capacity retention rate after 100 cycles at 0.1C was only 87.3%.

[0057] Comparative Example 3

[0058] Step S1: Nitrogen gas, 2.0 mol / L XSO4 (M = Ni, Co, Mn, where the molar ratio of Ni:Co:Mn is 0.90:0.05:0.05), 10.0 mol / L NaOH solution, and 10.0 mol / L ammonia water are simultaneously introduced into a reactor containing pure water, NaOH, and a nitrogen-containing complexing agent. The pH is maintained at 13.5, the ammonia concentration at 1.5 mol / L, the stirring speed at 12 m / s, the solution temperature at 80℃, the free nickel ion concentration at ≤50 ppm, and the dissolved oxygen content at <0.01 mg / L, until slurry D is obtained. 50 Reaching 5.0 μm; then continuously decreasing the pH to 12.0, and increasing the stirring speed to 9 m / s, until the slurry D... 50 Reaching 7.0μm;

[0059] Step S2: Continuously introduce 2.0 mol / L XSO4 (M = Ni, Co, Mn, where the molar ratio of Ni:Co:Mn is 0.90:0.05:0.05), 10.0 mol / L NaOH solution, 10.0 mol / L ammonia solution, and H2O2 solution into step S1. The amount of H2O2 solution added is 0.2 wt%. Adjust the ammonia concentration to 0.5 mol / L, the stirring linear speed to 7 m / s, the solution temperature to 80℃, the pH value to 11.0, the free nickel ion concentration to ≤30 ppm, and the dissolved oxygen content to 7.5 mg / L; until slurry D... 50 Feeding was stopped after the particle size reached 12.0 μm.

[0060] Step S3: Nitrogen gas is continuously introduced into the slurry from step S2. The solution temperature is 60℃ and the stirring speed is 5m / s until the dissolved oxygen content is ≤1.0mg / L. Then, 0.02mol / L citric acid is introduced for 30min. After aging and stirring for 200min, the precursor of the multi-element cathode material is obtained after washing and drying.

[0061] The precursor from step 3) was mixed evenly with LiOH·H2O, and then placed in a tube furnace. The temperature was increased to 600°C at a rate of 5°C / min and held for 8 hours. Then the temperature was increased to 900°C at a rate of 5°C / min and held for 15 hours to obtain the corresponding cathode material.

[0062] The cathode material prepared above was washed with water and modified by coating to prepare electrode sheets, which were then assembled into CR2032 coin cells. The electrochemical performance was tested, and the initial coulombic efficiency was 91.4%, the 0.1C cycle capacity was 213.4 mAh / g, and the capacity retention rate was 92.3% after 100 cycles at 0.1C.

[0063] Precursor particle size distribution data for the examples and comparative examples are shown in Table 1:

[0064] Group D 10 ]]> D 50 ]]> D 90 ]]> K 90 ]]> Example 1 8.97 11.92 16.87 0.66 Example 2 8.36 11.07 15.91 0.68 Example 3 7.93 10.06 14.68 0.67 Comparative Example 1 4.36 11.93 18.22 1.16 Comparative Example 2 5.95 12.04 18.03 1.00 Comparative Example 3 8.10 11.98 17.29 0.77

[0065] The relevant test data for the coin cell in the examples and comparative examples are shown in Tables 2 and 3:

[0066]

[0067] Table 2

[0068]

[0069]

[0070] Table 3

[0071] Based on the analysis of the above test data, the data in Tables 1-3 fully demonstrate that the composite oxidation regulation process of the embodiment significantly improves the stability of the precursor: narrow particle size distribution (K 90 ≤0.68), low proportion of small particles (D 10 (≥7.93μm) and excellent electrochemical performance (capacity retention >97%). The comparison between Example 1 and the comparative examples highlights the crucial role of oxidant type: the absence of an oxidant leads to an proliferation of small particles (Comparative Example 1), the improvement from the O3+ pH drop process is not significant (Comparative Example 2), and H2O2 alone also provides limited improvement (Comparative Example 3). However, the H2O2-O3 composite oxidation (Example 1), through real-time feedback control, effectively suppresses the formation of small particles, achieving the "synergistic optimization of particle size control and surface integrity" described in the patent. This provides a reliable material basis for high-energy-density lithium batteries.

[0072] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a multi-component cathode material precursor by controlling composite oxidation, characterized in that: Includes the following steps: Step S1: In a reactor containing pure water, NaOH, and a nitrogen-containing complexing agent, simultaneously introduce inert gas, a multi-component nickel-based sulfate solution, NaOH solution, and the nitrogen-containing complexing agent. Maintain the following conditions: pH 12.0-13.5, nitrogen-containing complexing agent concentration 0.5-1.5 mol / L, stirring speed 9-12 m / s, solution temperature 35-80℃, free nickel ion concentration ≤50 ppm, and dissolved oxygen content <0.01 mg / L, until slurry D... 50 Reach 2.0-5.0 μm; then continuously decrease the pH to 11.0-12.0, and increase the stirring speed to 7-9 m / s until the slurry D... 50 Reaching 5.0-7.0μm; Step S2: Continuously introduce a multi-component nickel-based sulfate solution, NaOH solution, nitrogen-containing complexing agent, and H2O2 solution into step S1. Adjust the nitrogen-containing complexing agent concentration to 0.1-0.5 mol / L, the stirring linear speed to 4-7 m / s, the solution temperature to 35-80℃, the pH value to 10.0-11.0, the free nickel ion concentration to ≤30 ppm, and the dissolved oxygen content to 6.0-7.5 mg / L. When the free nickel ion concentration is >30 ppm, introduce O3 until slurry D... 50 Feeding is stopped once the particle size reaches 7.0-12.0 μm. Step S3: Inert gas is continuously introduced into the slurry from step S2. The solution temperature is 50-60℃ and the stirring speed is 3-5m / s until the dissolved oxygen content is ≤1.0mg / L. Citric acid is then introduced for 10-30min, followed by aging and stirring for 30-200min. After washing and drying, the precursor of the multi-element cathode material is obtained.

2. The method for preparing a multi-element cathode material precursor by composite oxidation control according to claim 1, characterized in that: The nitrogen-containing complexing agent is one or a combination of several of the following: ammonia, ammonium sulfite, ammonium bisulfite, ammonium bisulfate, ammonium sulfide, ammonium hydrosulfide, ammonium thiosulfate, or ammonium carbonate; the inert gas is one or a combination of several of the following: nitrogen and argon.

3. The method for preparing a multi-element cathode material precursor by composite oxidation control according to claim 1, characterized in that: The multi-element nickel-based sulfate is XSO4, wherein X must contain Ni, the Ni element content is ≥80%, and the other elements are one or more of Co, Mn, Al, Mg, Ti, and Sr; the molar concentration of the XSO4 solution is 1.0-3.0 mol / L, the molar concentration of the NaOH solution is 2.0-15.0 mol / L, and the molar concentration of the nitrogen-containing complexing agent is 5.0-15.0 mol / L.

4. The method for preparing a multi-component cathode material precursor by composite oxidation control according to claim 1, characterized in that: The amount of H2O2 solution added is 0.01-0.2wt%, the amount of O3 introduced is 50-150ppm per time, the time of each time is 30-180s, and the interval between times is 5-10min; the concentration of citric acid is 0.005-0.02mol / L.

5. The method for preparing a multi-component cathode material precursor by composite oxidation control according to claim 1, characterized in that: The multi-component cathode material precursor is mixed evenly with a lithium-containing compound and then calcined. The lithium-containing compound is one or a combination of lithium hydroxide, lithium carbonate, lithium acetate, or lithium nitrate.

6. The method for preparing a multi-component cathode material precursor by composite oxidation control according to claim 1, characterized in that: The calcination step is as follows: heat to 400-600℃ at a rate of 3-5℃ / min, hold for 3-8 hours, then heat to 700-900℃ at a rate of 2-5℃ / min, and hold for 10-15 hours.

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