Lithium-rich manganese-based hydroxide precursor and preparation method thereof, positive electrode material, lithium ion battery and electric equipment

Abstract

The invention provides a lithium-rich manganese-based hydroxide precursor and a preparation method thereof, a positive electrode material, a lithium ion battery and electric equipment, and relates to the field of lithium ion batteries. The preparation method comprises the following steps: introducing a nickel-cobalt-manganese metal salt solution, an alkali solution and ammonia water into a base solution A, and carrying out a first reaction in a nitrogen atmosphere to obtain a crystal nucleus; introducing a crystal nucleus, a nickel-cobalt-manganese metal salt solution, ammonia water and an alkali solution into the base solution B, and carrying out a second reaction in nitrogen and oxygen-containing gas in sequence to obtain a lithium-rich manganese-based hydroxide precursor; in the second reaction process, along with the increase of the particle size, the pH is sequentially increased, and the alkalinity is sequentially reduced to 0 g / L. Under the condition of continuously increasing pH, the particles tend to grow along the surface energy reduction direction, and crystal grains agglomerated on the surfaces of the particles are easy to peel off for primary nucleation growth, so that the particles with small particle sizes are obtained, the particle size distribution range of the material is narrowed, and the tap density of the material is improved.

Description

Technical Field

[0001] This application relates to the field of lithium-ion batteries, and in particular to a lithium-rich manganese-based hydroxide precursor and its preparation method, a cathode material, a lithium-ion battery, and an electrical device. Background Technology

[0002] In recent years, the demand for lithium-ion power batteries has exploded, and high-energy-density cathode materials, as a key component of lithium-ion power batteries, have attracted widespread attention from researchers. Among them, lithium-rich manganese-based materials, which are also layered materials, have a specific capacity of over 250 mAh / g and an energy density of over 900 Wh·kg in the range of approximately 2.0V-4.8V. -1 The main raw materials are composed of relatively inexpensive Mn elements and have a low content of expensive Co elements. Therefore, LLOs cathode materials (lithium-rich manganese-based cathode materials) have the advantages of both high specific capacity and low cost, and are considered to be one of the most promising next-generation lithium-ion battery cathode materials.

[0003] Lithium-rich manganese-based cathode materials exhibit a high degree of inheritance in morphology and structure from their precursors. By controlling the morphology, structure, and composition of the precursors, the structure of lithium-rich manganese-based cathode materials can be effectively improved, suppressing structural deterioration, oxygen release, and side reactions. Currently, lithium-rich manganese-based precursors are mainly prepared using two co-precipitation methods: carbonate and hydroxide. When using the carbonate process, the low pH growth environment leads to incomplete precipitation of transition metals, causing component deviations and cost waste. Furthermore, the secondary spherical particles formed by the stacking of primary nanoparticles have problems such as low compaction density and excessive specific surface area, resulting in severe side reactions with the electrolyte under high voltage systems, gas generation, and other issues, making long-term cycling difficult. When using the hydroxide process, by precisely controlling the growth rate of the crystal nuclei, the thickness, porosity, and sphericity of the primary precursor particles are controlled, increasing the contact area between the material and the electrolyte, shortening the lithium-ion migration path, and improving the material's capacity and rate performance.

[0004] In existing technologies, although the pore structure of the precursor can be controlled by adding pore-forming agents to improve the morphology of the precursor, the synthesis and preparation process requires additional processes to remove the pore-forming agents, which are relatively complex, costly, and difficult to commercialize.

[0005] Therefore, there is an urgent need to provide a lithium-rich manganese-based hydroxide precursor to solve the above problems. Summary of the Invention

[0006] The purpose of this application is to provide a lithium-rich manganese-based hydroxide precursor and its preparation method, as well as a cathode material, a lithium-ion battery, and an electrical device, to solve the above-mentioned problems.

[0007] To achieve the above objectives, the first aspect of this application provides a method for preparing a lithium-rich manganese-based hydroxide precursor, comprising: A nickel-cobalt-manganese metal salt solution, an alkaline solution, and ammonia water are introduced into the bottom liquid A, and the first reaction is carried out under a nitrogen atmosphere to obtain crystal nuclei. The crystal nucleus, nickel-cobalt-manganese metal salt solution, ammonia and alkaline solution are introduced into the bottom liquid B, and the second reaction is carried out in nitrogen and oxygen-containing gas in sequence to obtain lithium-rich manganese-based hydroxide precursor. In the second reaction process, as the particle size increases, the pH increases sequentially, and the alkalinity decreases sequentially until it reaches 0 g / L.

[0008] Optionally, the method for preparing the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) During the second reaction, for every 1-3 µm increase in the D50 of the crystal nucleus, the pH increases by 0.1-0.2; (2) During the second reaction, for every 1-2 µm increase in the D50 of the crystal nucleus, the basicity decreases by 0.4-0.8 g / L; (3) During the second reaction, the time when the alkalinity is 0 g / L accounts for 3 / 4-5 / 6 of the total time of the second reaction; (4) In the second reaction process, the ammonia water is introduced for 1 / 8 to 1 / 4 of the total time of the second reaction.

[0009] Optionally, the method for preparing the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) In the second reaction, the time for which nitrogen gas is introduced accounts for 1 / 10 to 3 / 10 of the total time of the second reaction; (2) In the second reaction, the time for introducing the oxygen-containing gas accounts for 4 / 10 to 9 / 10 of the total time of the second reaction; (3) In the second reaction, the flow rate of nitrogen gas is 6-12 mL / min; (4) In the second reaction process, the introduction of oxygen-containing gas includes a first oxygen-containing gas introduction stage and a second oxygen-containing gas introduction stage performed sequentially; the oxygen content in the first oxygen-containing gas introduction stage is 4%-16%, and when the particle size of the crystal nucleus increases by 1-2 μm, the second oxygen-containing gas introduction stage is entered, and the oxygen content in the second oxygen-containing gas introduction stage is 20%-50% higher than that in the first oxygen-containing gas introduction stage; (5) The pH value of the second reaction is 9.20-10.40, and the temperature is 35-50℃; (6) The stirring speed for the second reaction is 120-300 rpm; (7) The solid content of the product slurry after the second reaction is 200-450 g / L; (8) The flow rate of the nickel-cobalt-manganese metal salt solution gradually increases during the second reaction process.

[0010] Optionally, the method for preparing the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) The D50 of the crystal nucleus is 1 / 5 to 2 / 5 of the D50 of the lithium-rich manganese-based hydroxide precursor; (2) The particle size of the crystal nuclei is 2.0-4.5 μm; (3) The pH value of the first reaction is 9.20-10.50, the alkalinity is 0-2g / L, and the temperature is 35-50℃.

[0011] Optionally, the method for preparing the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) The base liquid A and the base liquid B include water, alkaline solution and ammonia water; (2) The pH value of the bottom solution A is 9.40-10.50, and the alkalinity is 0-2 g / L; (3) The pH value of the bottom solution B is 9.0-10.0, and the alkalinity is 0-2 g / L; (4) The concentration of the nickel-cobalt-manganese metal salt solution is 1.5-2.2 mol / L; (5) The concentration of the alkaline solution is 9.0-14.0 mol / L; (6) The concentration of the ammonia water is 12.0-19.0 mol / L; (7) The stirring speed of the first reaction is 360-480 pm.

[0012] The second aspect of this application provides a lithium-rich manganese-based hydroxide precursor, which is prepared by the method for preparing the lithium-rich manganese-based hydroxide precursor.

[0013] Optionally, the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) The D50 of the lithium-rich manganese-based hydroxide precursor is 8-12 μm; (2) The tap density of the lithium-rich manganese-based hydroxide precursor is 1.6-1.9 g / cm³. 3 ; (3) The specific surface area of ​​the lithium-rich manganese-based hydroxide precursor is 25-45 m². 2 / g; (4) The porosity of the lithium-rich manganese-based hydroxide precursor is 15-30%; (5) The primary particle thickness of the lithium-rich manganese-based hydroxide precursor is 60-150 nm, the primary particle length is <650 nm, and the aspect ratio is 4.5-8.5. (6) The sphericity of the lithium-rich manganese-based hydroxide precursor is >0.82; (7) The general chemical formula of the lithium-rich manganese-based hydroxide precursor is Ni x Co y Mn z (OH)₂, where x + y + z = 1, 0.20 < x ≤ 0.40; 0.00 < y ≤ 0.20; 0.60 < z ≤ 0.85; (8) The secondary particles of the lithium-rich manganese-based hydroxide precursor include a core and an outer shell layer disposed on the surface of the core, wherein the primary particle thickness of the outer shell layer is greater than the primary particle thickness of the core. (9) The oil absorption of the lithium-rich manganese-based hydroxide precursor is 50-80 mL / 100 g.

[0014] The third aspect of this application provides a cathode material, the raw material of which is prepared by the method for preparing the lithium-rich manganese-based hydroxide precursor.

[0015] A fourth aspect of this application provides a lithium-ion battery, including the aforementioned positive electrode material.

[0016] The fifth aspect of this application provides an electrical device including the aforementioned lithium-ion battery.

[0017] Compared with the prior art, the beneficial effects of this application include: The method for preparing lithium-rich manganese-based hydroxide precursor provided in this application adjusts the pH of the reaction solution during the second reaction process, causing the surface of the resulting material particles to be in different growth states, thereby adjusting the surface morphology of the material. Under continuously increasing pH conditions, the particles tend to grow along the direction of decreasing surface energy, and the aggregated grains on the surface are easily peeled off for nucleation growth, thus obtaining more small-diameter particles, narrowing the particle size distribution range of the material, and thereby increasing the tap density of the material. At the same time, after the pH value is increased, due to the increase in the concentration of alkaline anions, the particles are refined under the tendency of grain orientation and accumulation, resulting in thinner whiskers on the particle surface, thereby increasing the specific surface area of ​​the material. In addition, in the early stage of nucleation growth in the second reaction process, a higher alkalinity is used to effectively control the concentration of free metal ions, thereby regulating the reaction rate, which is more conducive to the densification and homogenization of particle growth, while ensuring good sphericity of the precursor. In the middle and late stages of growth, the alkalinity is gradually reduced, and the pH is gradually increased in conjunction with the air oxidation process, and the growth reaction is carried out at a high pH to refine the particles and obtain a fine-densified precursor morphology. At the same time, the use of ammonia water is reduced, thus lowering production costs; the preparation process is stable, simple and controllable, and easy to mass-produce industrially.

[0018] The lithium-rich manganese-based hydroxide precursor provided in this application has good sphericity, high porosity, small aspect ratio, and high tap density.

[0019] The cathode material provided in this application has excellent rate performance, significantly increases the contact area between the material and the electrolyte, and shortens the migration path of lithium ions, thereby effectively improving the specific capacity and rate performance of the cathode material.

[0020] The lithium-ion battery and electrical equipment provided in this application have good capacity and rate performance. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0022] Figure 1 SEM image of the surface of the lithium-rich manganese-based hydroxide precursor provided in Example 1; Figure 2 A cross-sectional SEM image of the lithium-rich manganese-based hydroxide precursor provided in Example 1; Figure 3 XRD pattern of the lithium-rich manganese-based hydroxide precursor provided in Example 1; Figure 4 SEM image of the surface of the lithium-rich manganese-based hydroxide precursor provided for Comparative Example 8. Detailed Implementation

[0023] First, the solution provided in this application will be explained in more detail as follows: The first aspect of this application provides a method for preparing a lithium-rich manganese-based hydroxide precursor, comprising: A nickel-cobalt-manganese metal salt solution, an alkaline solution, and ammonia water are introduced into the bottom liquid A, and the first reaction is carried out under a nitrogen atmosphere to obtain crystal nuclei. The crystal nucleus, nickel-cobalt-manganese metal salt solution, ammonia and alkaline solution are introduced into the bottom liquid B, and the second reaction is carried out in nitrogen and oxygen-containing gas in sequence to obtain lithium-rich manganese-based hydroxide precursor. In the second reaction process, as the particle size increases, the pH increases sequentially, and the alkalinity decreases sequentially until it reaches 0 g / L.

[0024] It is important to note that during the synthesis reaction, under conventional synthesis conditions, the manganese-rich precursor has lower activity on the (001) face than the nickel precursor, making it prone to growing along the exposed (100) face, resulting in primary particles easily forming thick plates. By using a lower reaction temperature and buffering with low-concentration ammonia, the reaction rate is slowed down. The system is maintained in a rapid growth phase at a low pH, while maintaining high supersaturation under a nitrogen atmosphere reduces bulging and improves precursor sphericity. In the later stages of the reaction, under a low-temperature, ammonia-free system, the amount of air oxidation is controlled to manage the primary particle size, increasing the specific surface area of ​​the precursor and controlling its porosity. Simultaneously, increasing the salt flow rate and pH stepwise controls the length and density of the primary particles, improving the tap density of the precursor. By optimizing the precursor synthesis process, the morphology of the precursor can be effectively controlled, improving its structure and internal particle distribution. By increasing the porosity and sphericity of the precursor, a precursor with both high specific surface area and high tap density can be obtained.

[0025] In some embodiments, the method for preparing the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) During the second reaction, for every 1-3 µm increase in the D50 of the crystal nucleus, the pH increases by 0.1-0.2; Optionally, during the second reaction, for every increase of 1µm, 2µm, 3µm, or any value between 1 and 3µm in the D50 of the crystal nucleus, the pH can increase by 0.1, 0.15, 0.2, or any value between 0.1 and 0.2. It should be noted that if the pH rises too quickly, it can easily cause local nucleation of the particles, resulting in a wider particle size distribution and the production of small secondary particles (seeds); if the pH rises too slowly, the particle size growth rate is too fast, and the primary particles are coarse and long, making it difficult to obtain a fine, short and dense precursor morphology. (2) During the second reaction, for every 1-2 µm increase in the D50 of the crystal nucleus, the basicity decreases by 0.4-0.8 g / L; Optionally, during the second reaction, for every increase of 1µm, 1.5µm, 2µm, or any value between 1 and 2µm in the D50 of the crystal nucleus, the basicity can decrease by 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, or any value between 0.4 and 0.8 g / L. It should be noted that if the ammonia flow rate is too high and the alkalinity reduction rate is too fast during the alkalinity reduction process, the process control will be difficult and commercial reproducibility will be difficult. Too fast a reduction will cause the particle sphericity to deteriorate and the uniformity of the primary particles to deteriorate. If the alkalinity reduction rate is too slow, the particles will remain at low alkalinity for too long, resulting in coarse and long primary particles with a lower TD, which is not conducive to the performance of electrical properties. (3) During the second reaction, the time when the alkalinity is 0 g / L accounts for 3 / 4-5 / 6 of the total time of the second reaction; Optionally, during the second reaction, the duration of the alkalinity being 0 g / L can be any value between 9 / 12, 9.5 / 12, 10 / 12, or 3 / 4-5 / 6 of the total duration of the second reaction; It is worth noting that by controlling the oxidation amount of oxygen-containing gas in a low-temperature ammonia-free system to control the particle size, gradually increasing the salt flow rate, and rationally controlling the air flow rate, the pH is increased to control the length and density of the primary particles, resulting in a precursor with high porosity, small aspect ratio, high specific surface area, and high tap density. Maintaining a longer growth cycle in an ammonia-free environment is more conducive to the precursor morphology becoming finer, improving particle uniformity, and creating a loose and porous morphology. The difference in the size of the primary particles in the core and outer wall of the precursor is more conducive to the stable performance of the cathode material's electrical properties. (4) In the second reaction process, the ammonia water is introduced for 1 / 8 to 1 / 4 of the total time of the second reaction.

[0026] Optionally, in the second reaction process, the duration of ammonia infusion can be any value between 0.125, 0.15, 0.2, 0.25, or 0.125-0.25 of the total duration of the second reaction.

[0027] It is important to note that in the second reaction process, by using a lower reaction temperature and the buffering effect of a low concentration of ammonia water, the reaction rate is slowed down. Under a nitrogen atmosphere, a low pH is maintained to keep the system in a rapid growth phase. The grains that peel off from the particle surface can continue to grow, the whiskers continuously thicken, and the intergranular spaces are filled with new whiskers due to the precipitation of metal ions, reducing particle accumulation and bulging, while improving the sphericity of the precursor. In this way, the intercalation mode of the primary particles is improved, thereby improving the sphericity of the precursor, improving the uniformity of the particles, and obtaining a precursor with uniform particles and good sphericity.

[0028] In some embodiments, the method for preparing the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) In the second reaction, the time for which nitrogen gas is introduced accounts for 1 / 10 to 3 / 10 of the total time of the second reaction; Optionally, during the second reaction, the duration of nitrogen gas introduction can be any value between 1 / 10, 2 / 10, 3 / 10, or 1 / 10-3 / 10 of the total duration of the second reaction. (2) In the second reaction, the time for introducing the oxygen-containing gas accounts for 4 / 10 to 9 / 10 of the total time of the second reaction; Optionally, during the second reaction, the duration of introducing oxygen-containing gas accounts for any value between 4 / 10, 5 / 10, 6 / 10, 7 / 10, 8 / 10, 9 / 10, or 4 / 10-9 / 10 of the total duration of the second reaction; (3) In the second reaction, the flow rate of nitrogen gas is 6-12 mL / min; Optionally, during the second reaction, the flow rate of nitrogen can be any value between 6 mL / min, 8 mL / min, 10 mL / min, 12 mL / min, or 6-12 mL / min; (4) In the second reaction process, the introduction of oxygen-containing gas includes a first oxygen-containing gas introduction stage and a second oxygen-containing gas introduction stage performed sequentially; the oxygen content in the first oxygen-containing gas introduction stage is 4%-16%, and when the particle size of the crystal nucleus increases by 1-2 μm, the second oxygen-containing gas introduction stage is entered, and the oxygen content in the second oxygen-containing gas introduction stage is 20%-50% higher than that in the first oxygen-containing gas introduction stage; Optionally, the oxygen content in the first oxygen-containing gas introduction stage can be any value between 4%, 6%, 8%, 10%, 12%, 14%, 16%, or 4%-16%. When the particle size of the crystal nucleus increases by any value between 1μm, 1.5μm, 2μm, or 1-2μm, the oxygen content in the second oxygen-containing gas introduction stage can increase by any value between 20%, 30%, 40%, 50%, or 20%-50% compared to the oxygen content in the first oxygen-containing gas introduction stage. It is worth noting that when faced with the problem that the primary particles of the precursor tend to be thick and plate-like, making it difficult to refine them, this application addresses this issue by quantitatively controlling the amount of air introduced (increasing the amount of air introduced by 20%-50% on the basis of the original method). By controlling the supersaturation in the solution during the instantaneous growth process, the original nucleation-growth balance is broken near the critical point, causing the reaction to proceed in a direction dominated by explosive nucleation. This finely controls the crystal morphology, promotes a change in the growth mode of the primary particles, refines the morphology, and makes the distribution between particles more loose. This results in a precursor with a high specific surface area, loose and porous distribution, high porosity, and fine primary particles. This reduces the cracks caused by uneven shrinkage of the precursor during sintering, thereby reducing the compaction density and cycle stability of the cathode material. (5) The pH value of the second reaction is 9.20-10.40, and the temperature is 35-50℃; Optionally, the pH value of the second reaction can be any value between 9.20, 9.5, 10, 10.4 or 9.20-10.40, and the temperature can be any value between 35℃, 40℃, 45℃, 50℃ or 35-50℃. It is important to note that the pH and air flow rate are particularly important during the air oxidation process. At high pH, ​​the precursor is more prone to bulging. Lowering the reaction pH of the system can increase the supersaturation, keep the system in the rapid growth stage, solve the bulging problem caused by the reduction of supersaturation due to oxidation, and improve the sphericity of the precursor. (6) The stirring speed for the second reaction is 120-300 rpm; Optionally, the stirring speed of the second reaction can be any value between 120 rpm, 150 rpm, 200 rpm, 300 rpm, or 120-300 rpm; (7) The solid content of the product slurry after the second reaction is 200-450 g / L; Optionally, the solid content of the product slurry after the second reaction can be any value between 200 g / L, 250 g / L, 350 g / L, 450 g / L, or 200-450 g / L. (8) The flow rate of the nickel-cobalt-manganese metal salt solution gradually increases during the second reaction process.

[0029] In some embodiments, the initial flow rate of the nickel-cobalt-manganese metal salt solution in the second reaction process is 60-300 mL / min, and the final flow rate at the end is 400-800 mL / min.

[0030] Optionally, the initial flow rate of the nickel-cobalt-manganese metal salt solution in the second reaction process can be any value between 60 mL / min, 100 mL / min, 200 mL / min, 300 mL / min, or 60-300 mL / min, and the final flow rate at the end can be any value between 400 mL / min, 500 mL / min, 600 mL / min, 700 mL / min, 800 mL / min, or 400-800 mL / min.

[0031] In some embodiments, the method for preparing the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) The D50 of the crystal nucleus is 1 / 5 to 2 / 5 of the D50 of the lithium-rich manganese-based hydroxide precursor; Optionally, the D50 of the crystal nucleus can be any value between 1 / 5, 3 / 10, 2 / 5 or 1 / 5-2 / 5 of the D50 of the lithium-rich manganese-based hydroxide precursor; (2) The particle size of the crystal nuclei is 2.0-4.5 μm; Optionally, the particle size of the crystal nucleus can be 2μm, 2.5μm, 3.5μm, 4.5μm or any value between 2.0 and 4.5μm; (3) The pH value of the first reaction is 9.20-10.50, the alkalinity is 0-2g / L, and the temperature is 35-50℃.

[0032] Optionally, the pH value of the first reaction can be any value between 9.2, 9.5, 10, 10.5 or 9.20-10.50, the alkalinity can be any value between 0, 1, 2 g / L or 0-2 g / L, and the temperature can be any value between 35℃, 40℃, 45℃, 50℃ or 35-50℃.

[0033] In some embodiments, the method for preparing the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) The base liquid A and the base liquid B include water, alkaline solution and ammonia water; (2) The pH value of the bottom solution A is 9.40-10.50, and the alkalinity is 0-2 g / L; Optionally, the pH of the base solution A can be any value between 9.40, 9.5, 10, 10.5 or 9.40-10.50, and the alkalinity can be any value between 0, 1, 2 g / L or 0-2 g / L; (3) The pH value of the bottom solution B is 9.0-10.0, and the alkalinity is 0-2 g / L; Optionally, the pH value of the substrate B can be any value between 9.0, 9.2, 9.40, 9.5, 10, 10.5 or 9.0-10.0, and the alkalinity can be any value between 0, 1, 2 g / L or 0-2 g / L; (4) The concentration of the nickel-cobalt-manganese metal salt solution is 1.5-2.2 mol / L; Optionally, the concentration of the nickel-cobalt-manganese metal salt solution can be any value between 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, 2.1 mol / L, 2.2 mol / L, or 1.5-2.2 mol / L; (5) The concentration of the alkaline solution is 9.0-14.0 mol / L; Optionally, the concentration of the alkaline solution can be 9 mol / L, 10 mol / L, 11 mol / L, 12 mol / L, 13 mol / L, 14 mol / L or any value between 9.0 and 14.0 mol / L; (6) The concentration of the ammonia water is 12.0-19.0 mol / L; Optionally, the concentration of ammonia can be any value between 12 mol / L, 13 mol / L, 14 mol / L, 15 mol / L, 16 mol / L, 17 mol / L, 18 mol / L, 19 mol / L, or 12.0-19.0 mol / L; (7) The stirring speed of the first reaction is 360-480 pm.

[0034] Optionally, the stirring speed for the first reaction can be any value between 360 pm, 400 pm, 440 pm, 480 pm, or 360-480 pm.

[0035] It is worth noting that this application systematically studied the matching of temperature, alkalinity, and pH in the synthesis conditions of lithium-rich manganese-based precursor materials, and the morphology and sphericity of the primary particles of the precursor. By adjusting the synergistic effect of suitable temperature, alkalinity, and pH ranges, the morphology of the primary particles of the precursor was regulated, resulting in a precursor with uniform particle size and high porosity. The uniformity of the primary particles broadened the ion shuttle channels. At the same time, the fine strip-shaped primary particles were less prone to loosening, maintaining the structural stability of the secondary particles and improving the electrical performance of the lithium-rich manganese-based cathode material: during charge and discharge in the range of 2.5-4.5V, the charging capacity was ≥280mAh / g, and the discharging capacity was ≥230mAh / g. By rationally selecting the seed morphology, particle size, and seed weight, and controlling the lower reaction and drying temperatures, the formation of impurity phases was avoided. At the same time, the solid content of the product and the D50 change rate of the precursor product were controlled, resulting in a precursor with high specific surface area, high tap density, and good sphericity.

[0036] The second aspect of this application provides a lithium-rich manganese-based hydroxide precursor, which is prepared by the method for preparing the lithium-rich manganese-based hydroxide precursor.

[0037] In some embodiments, the lithium-rich manganese-based hydroxide precursor satisfies at least one of the following conditions: (1) The D50 of the lithium-rich manganese-based hydroxide precursor is 8-12 μm; Optionally, the D50 of the lithium-rich manganese-based hydroxide precursor can be any value between 8 μm, 10 μm, 12 μm, or 8-12 μm; (2) The tap density of the lithium-rich manganese-based hydroxide precursor is 1.6-1.9 g / cm³. 3 ; Optionally, the tap density of the lithium-rich manganese-based hydroxide precursor can be 1.6 g / cm³. 3 1.7g / cm 3 1.8g / cm 3 1.9g / cm 3 Or 1.6-1.9 g / cm³ 3 Any value between; (3) The specific surface area of ​​the lithium-rich manganese-based hydroxide precursor is 25-45 m². 2 / g; Optionally, the specific surface area of ​​the lithium-rich manganese-based hydroxide precursor can be 25 m². 2 / g、35m 2 / g、45m 2 / g or 25-45m 2 Any value between / g; (4) The porosity of the lithium-rich manganese-based hydroxide precursor is 15-30%; Optionally, the porosity of the lithium-rich manganese-based hydroxide precursor can be any value between 15%, 20%, 25%, 30%, or 15-30%. (5) The primary particle thickness of the lithium-rich manganese-based hydroxide precursor is 60-150 nm, the primary particle length is <650 nm, and the aspect ratio is 4.5-8.5. Optionally, the primary particle thickness of the lithium-rich manganese-based hydroxide precursor can be any value between 60 nm, 100 nm, 150 nm, or 60-150 nm; the primary particle length can be any value between 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, or <650 nm; and the aspect ratio can be any value between 4.5, 5, 6, 7, 8, 8.5, or 4.5-8.5. It should be noted that when the aspect ratio is 4.5-8.5, more surface active sites can be provided, increasing the contact area with the electrolyte, shortening the lithium ion migration path, and improving rate performance. (6) The sphericity of the lithium-rich manganese-based hydroxide precursor is >0.82; Optionally, the sphericity of the lithium-rich manganese-based hydroxide precursor can be any value of 0.85, 0.9, 0.95 or >0.82; (7) The general chemical formula of the lithium-rich manganese-based hydroxide precursor is Ni x Co y Mn z (OH)₂, where x + y + z = 1, 0.20 < x ≤ 0.40; 0.00 < y ≤ 0.20; 0.60 < z ≤ 0.85; Optionally, x can be any value between 0.21, 0.3, 0.4, or greater than 0.2 and less than or equal to 0.4; y can be any value between 0.01, 0.1, 0.2, or greater than 0 and less than or equal to 0.2; and z can be any value between 0.61, 0.65, 0.7, 0.8, 0.85, or greater than 0.6 and less than or equal to 0.85. (8) The secondary particles of the lithium-rich manganese-based hydroxide precursor include a core and an outer shell layer disposed on the surface of the core, wherein the primary particle thickness of the outer shell layer is greater than the primary particle thickness of the core. (9) The oil absorption of the lithium-rich manganese-based hydroxide precursor is 50-80 mL / 100 g.

[0038] Optionally, the oil absorption capacity of the lithium-rich manganese-based hydroxide precursor can be any value between 50 mL / 100g, 60 mL / 100g, 70 mL / 100g, 80 mL / 100g, or 50-80 mL / 100g.

[0039] The third aspect of this application provides a cathode material, the raw material of which is prepared by the method for preparing the lithium-rich manganese-based hydroxide precursor.

[0040] It should be noted that this cathode material is prepared using the aforementioned lithium-rich manganese-based hydroxide precursor as a raw material. Conventionally, it is prepared by calcining the lithium-rich manganese-based hydroxide precursor prepared above with a lithium source, or by calcining the lithium-rich manganese-based hydroxide precursor prepared above with a lithium source and a doped metal source. When doping is performed, the doping element can be conventional modified element cations, anions, or dual cation and anion doping of lithium-rich manganese-based materials.

[0041] A fourth aspect of this application provides a lithium-ion battery, including the aforementioned positive electrode material.

[0042] The fifth aspect of this application provides an electrical device including the aforementioned lithium-ion battery.

[0043] It should be noted that electrical equipment may include, but is not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc.; among them, mobile devices may include, but are not limited to, at least one of mobile phones, laptops, etc.; electric vehicles may include, but are not limited to, at least one of pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.

[0044] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0045] Example 1 The first aspect of this embodiment provides a lithium-rich manganese-based hydroxide precursor and its preparation method, the specific preparation steps of which are as follows: S1: Based on the molecular formula Ni 0.35 Mn 0.65 Prepare a 2 mol / L nickel-cobalt-manganese mixed metal salt solution using (OH)2; prepare a 10 mol / L sodium hydroxide solution; prepare a 16 mol / L ammonia solution. S2: Add 100L of pure water to a 300L reactor, control the temperature at 50℃, and the stirring speed at 420rpm. Purge with sodium hydroxide solution to adjust the pH to 10.40±0.05. Continuously purge nitrogen into the reactor. In the bottom liquid of the reactor, simultaneously purge with the nickel-cobalt-manganese metal salt solution, alkaline solution, and ammonia water prepared in S1. During the reaction, continuously purge with nitrogen, maintain the reaction temperature at 50℃, and the stirring speed at 420rpm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution is 360mL / min. After the reaction begins, the molar ratio of the nickel-cobalt-manganese mixed metal salt solution to the sodium hydroxide solution is 1:2.2. After 30 minutes of nucleation, adjust the flow rate of the sodium hydroxide solution to stabilize the pH in the reactor at 9.60±0.05, and control the ammonia ion concentration in the reactor to 0g / L. Stop the reaction when the product D50 in the reactor reaches 4.0±0.2μm. Wash and filter the product to obtain the ternary precursor nuclei. S3: Add 200L of pure water to the reactor, control the temperature to 40℃, and control the stirring speed to 360rpm. Add the crystal nuclei obtained in step S2, and adjust the alkalinity in the reactor to 2g / L by introducing ammonia solution. In the bottom liquid of the reactor, simultaneously introduce the nickel-cobalt-manganese metal salt solution, alkaline solution, and ammonia solution prepared in S1 to react. During the reaction, continuously introduce nitrogen gas into the reactor for 8 hours (10mL / min). The reaction temperature is 40℃, and the initial stirring speed is 360rpm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution is 240mL / min. Control the ammonium ion concentration in the reactor to about 2g / L and maintain the pH value in the reactor at 9.30±0.05. At the end of the nitrogen reaction, the particle size D50 increases to 6±0.5µm, and the flow rate of the nickel-cobalt-manganese mixed metal salt solution is adjusted to 480mL / min. The ammonium ion concentration in the reactor was controlled at approximately 0.5 g / L, and the pH value was stabilized at 9.60 ± 0.05. Then, air was introduced for 7 hours (oxygen content 6%). At the end of the 7-hour air introduction, the particle size D50 increased to 8 ± 0.5 µm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution was 720 mL / min, and the ammonium ion concentration in the reactor was controlled at approximately 0 g / L, with the pH value stabilized at 10.00 ± 0.05. Air was continued for 49 hours (oxygen content increased by 50% compared to the previous stage), until the reaction product D50 reached 10.0 ± 0.5 µm and the pH value stabilized at 10.30 ± 0.05. The next stage then began, and at the end of the reaction, the solid content in the reactor was 250 g / L. Throughout the entire S3 reaction process, the ammonia water was introduced for 10 hours during the second reaction. S4: The reaction product obtained in S3 is aged, washed, filtered, and dried. It is aged in 10wt% alkaline solution at 70℃ for 60min. The final pH value of washing is controlled at 8.2. The drying temperature is 70℃.

[0046] Surface SEM images of the lithium-rich manganese-based hydroxide precursor are shown below. Figure 1 As shown, from Figure 1 As can be seen, the obtained precursor has a fine and dense primary particle distribution, with a loose and porous particle distribution and good sphericity. The sintered cathode material exhibits good inheritance, with a regular primary particle distribution and good sphericity. SEM cross-sectional images of the obtained precursor and cathode material are shown below. Figure 2 As shown in the figure, the obtained precursor primary particles have a strip-like structure with a loose and porous distribution. The outer wall is denser, while the interior is loose and porous, with the internal primary particles shorter than the outer wall particles. The cathode material inherits the cross-sectional morphology of the precursor. After testing its porosity, the porosity of the precursor is 23%, and that of the cathode material is 9%. The XRD pattern of the obtained lithium-rich manganese-based hydroxide precursor is shown in the figure. Figure 3 As shown, the main characteristic peaks are those of the Ni(OH)2 phase, and no Mn3O4 phase diffraction peaks are observed.

[0047] The second aspect of this application provides a cathode material, the specific preparation method of which is as follows: The precursor obtained from S4 was mixed with lithium carbonate at a molar ratio of 1:1.33 to obtain a lithium mixed sintering precursor. The lithium mixed sintering precursor was placed in an air atmosphere muffle furnace and heated to 500°C at 3°C / min and held for 5 hours. Then, the temperature was increased to 800°C at 3°C / min and held for 10 hours to obtain a lithium-rich manganese-based cathode material.

[0048] Example 2 The difference from Example 1 is as follows: In step S3, 200L of pure water is added to the reactor, the temperature is controlled at 40℃, the stirring speed is controlled at 360rpm, the crystal nuclei obtained in step S2 are added, and the alkalinity in the reactor is adjusted to 2g / L by introducing ammonia solution. The nickel-cobalt-manganese metal salt solution, alkaline solution, and ammonia solution prepared in step S1 are introduced into the bottom liquid of the reactor in parallel for reaction. During the reaction, nitrogen gas is continuously introduced into the reactor for 8 hours (10mL / min), the reaction temperature is 40℃, the initial stirring speed is 360rpm, the flow rate of the nickel-cobalt-manganese mixed metal salt solution is 240mL / min, the ammonium ion concentration in the reactor is controlled at about 2g / L, and the pH value in the reactor is controlled to be stable at 9.20±0.05. At the end of the nitrogen reaction, the particle size D50 increases to 6±0.5µm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution was adjusted to 480 mL / min, and the ammonium ion concentration in the reactor was controlled at approximately 0.5 g / L, with the pH value stabilized at 9.30 ± 0.05. Then, air was introduced for 7 hours (oxygen content of 8%). At the end of the 7-hour air introduction, the particle size D50 increased to 8 ± 0.5 µm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution was then adjusted to 720 mL / min, and the ammonium ion concentration in the reactor was controlled at approximately 0 g / L, with the pH value stabilized at 9.40 ± 0.05. Air was introduced for another 49 hours (the oxygen content increased by 50% compared to the previous stage). After the reaction product D50 reached 10.0 ± 0.5 µm, the pH value stabilized at 9.50 ± 0.05, and the next stage began. At the end of the reaction, the solid content in the reactor was 250 g / L.

[0049] Example 3 The difference from Example 1 is as follows: In step S3, 200L of pure water is added to the reactor, the temperature is controlled at 40℃, the stirring speed is controlled at 360rpm, the crystal nuclei obtained in step S2 are added, and the alkalinity in the reactor is adjusted to 2g / L by introducing ammonia solution. The nickel-cobalt-manganese metal salt solution, alkaline solution and ammonia solution prepared in step S1 are introduced into the bottom liquid of the reactor in parallel for reaction. During the reaction, nitrogen gas is continuously introduced into the reactor for 8 hours (10mL / min), the reaction temperature is 40℃, the initial stirring speed is 360rpm, the flow rate of the nickel-cobalt-manganese mixed metal salt solution is 240mL / min, the ammonium ion concentration in the reactor is controlled at about 2g / L, and the pH value in the reactor is controlled to be stable at 9.30±0.05. At the end of the nitrogen reaction, the particle size D50 increases. The particle size was increased to 6±0.5µm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution was adjusted to 480mL / min, and the ammonium ion concentration in the reactor was controlled at about 1.6g / L, with the pH value stabilized at 9.60±0.05. Then, air was introduced for 7h (oxygen content of 10%). At the end of the 7h air introduction, the particle size D50 increased to 8±0.5µm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution was adjusted to 720mL / min, and the ammonium ion concentration in the reactor was controlled at about 0g / L, with the pH value stabilized at 10.00±0.05. Air was introduced for another 49h (the oxygen content increased by 50% compared to the previous stage). After the reaction product D50 reached 10.0±0.5µm, the next stage was started. At the end of the reaction, the solid content in the reactor was 250g / L.

[0050] Comparative Example 1 The difference from Example 1 is that in step S3, only air is added.

[0051] Comparative Example 2 The difference from Example 1 is that in step S3, only nitrogen is added.

[0052] Comparative Example 3 The difference from Example 1 is that the ammonium ion concentration is always 2 g / L in step S3.

[0053] Comparative Example 4 The difference from Example 1 is that in step S3, the pH value remains stable at 9.30±0.05.

[0054] Comparative Example 5 The difference from Example 1 is that in step S3, the concentration of ammonium ions is controlled to decrease, but the concentration of ammonium ions is 0.1 g / L at the end of the reaction.

[0055] Comparative Example 6 The difference from Example 1 is that in step S3, the pH value is controlled to increase with the increase of particle size. After continuing to introduce air for 49 hours, the pH value stabilizes at 10.60±0.05 when the reaction product D50 reaches 10.0±0.5µm.

[0056] Comparative Example 7 The difference from Example 1 is as follows: In step S3, air is introduced for 15 hours. At the end of the 7-hour air passage, the particle size D50 increases to 8±0.5µm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution is 720mL / min. The ammonium ion concentration in the reactor is controlled to be around 0g / L. Air is then introduced for another 41 hours until the reaction product D50 reaches 10.0±0.5µm, at which point the reaction is terminated. That is, during the second reaction, the time when the alkalinity is 0 g / L accounts for 0.359375 of the total time of the second reaction.

[0057] Comparative Example 8 The first aspect of this embodiment provides a lithium-rich manganese-based hydroxide precursor and its preparation method, the specific preparation steps of which are as follows: S1: Based on the molecular formula Ni 0.35 Mn 0.65 Prepare a 2 mol / L nickel-cobalt-manganese mixed metal salt solution using (OH)2; prepare a 10 mol / L sodium hydroxide solution; prepare a 16 mol / L ammonia solution. S2: Add 100L of pure water to a 300L reactor, control the temperature at 65℃, and the stirring speed at 480rpm. Purge sodium hydroxide solution to adjust the pH to 10.80±0.05, and continuously purge nitrogen into the reactor. In the bottom liquid of the reactor, simultaneously purge the nickel-cobalt-manganese metal salt solution, alkaline solution, and ammonia water prepared in S1. During the reaction, continuously purge nitrogen into the reactor, maintain the reaction temperature at 65℃, and the stirring speed at 420rpm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution is 360mL / min. After the reaction begins, the molar ratio of the nickel-cobalt-manganese mixed metal salt solution to the sodium hydroxide solution is 1:2.2. After 30 minutes of nucleation, adjust the flow rate of the sodium hydroxide solution to stabilize the pH in the reactor at 9.60±0.05, and control the ammonia ion concentration in the reactor to 4g / L. Stop the reaction when the product D50 in the reactor reaches 4.0±0.2μm. Wash and filter the product to obtain the ternary precursor nuclei. S3: Add 200L of pure water to the reactor, control the temperature to 65℃, and control the stirring speed to 360rpm. Add the crystal nuclei obtained in step S2, and adjust the alkalinity of the reactor to 5g / L by introducing ammonia solution. Introduce the nickel-cobalt-manganese metal salt solution, alkaline solution, and ammonia solution prepared in step S1 into the bottom liquid of the reactor in a parallel flow to carry out the reaction. During the reaction, continuously introduce nitrogen gas into the reactor for 8 hours (10mL / min). The reaction temperature is 40℃, and the initial stirring speed is 480rpm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution is 120mL / min, and the ammonium ion concentration in the reactor is controlled to be 5g / L. The pH value inside the reactor was controlled at approximately 10.60±0.05. At the end of the nitrogen reaction, the particle size D50 increased to 6±0.5µm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution was adjusted to 360mL / min, and the ammonium ion concentration inside the reactor was controlled at approximately 0.5g / L, with the pH value stabilized at 9.60±0.05. Then, air was introduced for 7 hours. At the end of the 7-hour air reaction, the particle size D50 increased to 8±0.5µm. The flow rate of the nickel-cobalt-manganese mixed metal salt solution was 360mL / min. When the D50 of the reaction product reached 10.0±0.5µm, the next stage was initiated. S4: The reaction product obtained in S3 is aged, washed, filtered, and dried. It is aged in 10wt% alkaline solution at 70℃ for 60min. The final pH value of washing is controlled at 8.2. The drying temperature is 80℃.

[0058] SEM images of the lithium-rich manganese-based hydroxide precursor are shown below. Figure 4 As shown, the precursor particles exhibit significant differences, uneven particle distribution, and poor sphericity.

[0059] The relevant parameters of the lithium-rich manganese-based hydroxide precursors prepared in the above embodiments and comparative examples are shown in Table 1.

[0060] Table 1 Relevant Parameters

[0061] The positive electrode materials prepared in the above examples and comparative examples were subjected to electrochemical performance testing using a button cell. The positive electrode material, conductive carbon black, and PVDF (polyvinylidene fluoride) binder were mixed in a ratio of 8.5:1.5:1.5 to form a slurry, which was then coated onto aluminum foil to form the positive electrode sheet. A lithium metal sheet was used as the negative electrode sheet, and a 1 mol / L LiPF6 / EC:DMC electrolyte (volume ratio 1:1) was used. The battery casing, positive and negative electrode sheets, separator, spring contacts, and gaskets were assembled into a button cell in a vacuum glove box. Cyclic voltammetry (CV) and AC impedance spectroscopy were performed on a SolartonMetrology electrochemical workstation, with a voltage perturbation of 5 mV and a frequency range of 10 mHz to 100 kHz. Specific test results are shown in Table 2.

[0062] Table 2 Electrochemical Performance Tests

[0063] analyze: As can be seen from the above tests, under the process of the preparation method of lithium-rich manganese-based hydroxide precursor provided in this application, the cathode material corresponding to the prepared lithium-rich manganese-based hydroxide precursor has a higher overall charge-discharge capacity and higher coulombic efficiency compared with the comparative example, showing excellent electrochemical performance. This confirms that the preparation method of lithium-rich manganese-based hydroxide precursor effectively controls the morphology of the precursor, improves the morphology and structure of the precursor, and helps to bring out the electrical performance of the cathode material.

[0064] Compared to Example 1, in Comparative Example 1, under the condition of adding only air and in a low pH and ammonia-free environment, the precursor in the air environment during the early stage of growth caused the particles to accumulate too quickly due to excessive supersaturation, resulting in bulging. The primary particle morphology of the precursor was too long, making it difficult to refine.

[0065] Compared to Example 1, in Comparative Example 2 under a nitrogen atmosphere, as the reaction period lengthened and the solid content of the reaction increased, the particles could not be refined, and the particles were distributed in a coarse blocky shape, with a significantly lower specific surface area index.

[0066] Compared to Example 1, in Comparative Example 3 with an alkalinity of 2 g / L, due to the effect of alkalinity, as the pH continuously increases, the higher pH value reduces the relative supersaturation of the solution, reduces the number of nuclei, and promotes grain growth. At the same time, alkaline conditions may change the charge state of the precipitate surface or promote the Ostwald ripening process, causing small particles to dissolve and large particles to grow. The precipitation rate is relatively slow, and the particle surface uniformity is good. However, due to the continuous increase in the concentration point and the increase in air volume, the particles are coarser and the tap density is high. However, due to the presence of ammonia, the particles are not refined.

[0067] Compared to Example 1, Comparative Example 4 had a fixed pH, which did not achieve the coordinated effect of pH and air flow. The test point was lower, and although the particles were refined, the primary particles were longer. The specific surface area was higher, but the TD was lower, and the capacity was not effectively utilized during the electrical performance test.

[0068] Compared to Example 1, the precursor properties of Comparative Example 5 at an alkalinity of 2-1.0 g / L were similar to those of Comparative Example 3. The supersaturation was regulated by the presence of ammonia, but the specific surface area was low and the electrical performance was poor.

[0069] Compared to Example 1, in Comparative Example 6, as the pH continued to increase, the precursor underwent secondary nucleation due to the excessively high pH level. This resulted in a large number of fine particles appearing on the surface of the precursor, affecting the uniformity of the particles and causing an increase in the aspect ratio of the particles.

[0070] Compared to Example 1, Comparative Example 7 adjusted the alkalinity to 0 g / L in the later stage of the reaction cycle, which did not reach the time point for particle formation and the particles did not achieve a fine distribution.

[0071] Compared to Example 1, Comparative Example 8 had an initial alkalinity of less than 5 g / L. Due to the excessive alkalinity, the particles exhibited a coarse blocky distribution. Furthermore, because the particles were too coarse in the early stage, the particles were not refined in the later growth stage, resulting in uneven particle size and poor sphericity.

[0072] Finally, it should be noted that the above 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0073] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing a lithium-rich manganese-based hydroxide precursor, characterized in that, include: A nickel-cobalt-manganese metal salt solution, an alkaline solution, and ammonia water are introduced into the bottom liquid A, and the first reaction is carried out under a nitrogen atmosphere to obtain crystal nuclei. The crystal nucleus, nickel-cobalt-manganese metal salt solution, ammonia and alkaline solution are introduced into the bottom liquid B, and the second reaction is carried out in nitrogen and oxygen-containing gas in sequence to obtain lithium-rich manganese-based hydroxide precursor. In the second reaction process, as the particle size increases, the pH increases sequentially, and the alkalinity decreases sequentially until it reaches 0 g / L.

2. The method for preparing the lithium-rich manganese-based hydroxide precursor according to claim 1, characterized in that, At least one of the following conditions must be met: (1) During the second reaction, for every 1-3 µm increase in the D50 of the crystal nucleus, the pH increases by 0.1-0.2; (2) During the second reaction, for every 1-2 µm increase in the D50 of the crystal nucleus, the basicity decreases by 0.4-0.8 g / L; (3) During the second reaction, the time when the alkalinity is 0 g / L accounts for 3 / 4-5 / 6 of the total time of the second reaction; (4) During the second reaction process, the ammonia water is introduced for 1 / 8 to 1 / 4 of the total time of the second reaction.

3. The method for preparing the lithium-rich manganese-based hydroxide precursor according to claim 1, characterized in that, At least one of the following conditions must be met: (1) During the second reaction, the time for which nitrogen gas is introduced accounts for 1 / 10 to 3 / 10 of the total time of the second reaction; (2) During the second reaction, the time for introducing the oxygen-containing gas accounts for 4 / 10 to 9 / 10 of the total time of the second reaction; (3) During the second reaction process, the flow rate of nitrogen gas is 6-12 mL / min; (4) In the second reaction process, the introduction of oxygen-containing gas includes a first oxygen-containing gas introduction stage and a second oxygen-containing gas introduction stage performed sequentially; the oxygen content in the first oxygen-containing gas introduction stage is 4%-16%, and when the particle size of the crystal nucleus increases by 1-2 μm, the second oxygen-containing gas introduction stage is entered, and the oxygen content in the second oxygen-containing gas introduction stage is 20%-50% higher than that in the first oxygen-containing gas introduction stage; (5) The pH value of the second reaction is 9.20-10.40, and the temperature is 35-50℃; (6) The stirring speed for the second reaction is 120-300 rpm; (7) The solid content of the product slurry after the second reaction is 200-450 g / L; (8) The flow rate of the nickel-cobalt-manganese metal salt solution gradually increases during the second reaction process.

4. The method for preparing the lithium-rich manganese-based hydroxide precursor according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The D50 of the crystal nucleus is 1 / 5 to 2 / 5 of the D50 of the lithium-rich manganese-based hydroxide precursor; (2) The particle size of the crystal nuclei is 2.0-4.5 μm; (3) The pH value of the first reaction is 9.20-10.50, the alkalinity is 0-2g / L, and the temperature is 35-50℃.

5. The method for preparing the lithium-rich manganese-based hydroxide precursor according to any one of claims 1-4, characterized in that, At least one of the following conditions must be met: (1) The base liquid A and the base liquid B include water, alkaline solution and ammonia water; (2) The pH value of the bottom solution A is 9.40-10.50, and the alkalinity is 0-2 g / L; (3) The pH value of the bottom solution B is 9.0-10.0, and the alkalinity is 0-2 g / L; (4) The concentration of the nickel-cobalt-manganese metal salt solution is 1.5-2.2 mol / L; (5) The concentration of the alkaline solution is 9.0-14.0 mol / L; (6) The concentration of the ammonia water is 12.0-19.0 mol / L; (7) The stirring speed of the first reaction is 360-480 pm.

6. A lithium-rich manganese-based hydroxide precursor, characterized in that, It is prepared by the method for preparing lithium-rich manganese-based hydroxide precursor according to any one of claims 1-5.

7. The lithium-rich manganese-based hydroxide precursor according to claim 6, characterized in that, At least one of the following conditions must be met: (1) The D50 of the lithium-rich manganese-based hydroxide precursor is 8-12 μm; (2) The tap density of the lithium-rich manganese-based hydroxide precursor is 1.6-1.9 g / cm³. 3 ; (3) The specific surface area of ​​the lithium-rich manganese-based hydroxide precursor is 25-45 m². 2 / g; (4) The porosity of the lithium-rich manganese-based hydroxide precursor is 15-30%; (5) The primary particle thickness of the lithium-rich manganese-based hydroxide precursor is 60-150 nm, the primary particle length is <650 nm, and the aspect ratio is 4.5-8.

5. (6) The sphericity of the lithium-rich manganese-based hydroxide precursor is >0.82; (7) The general chemical formula of the lithium-rich manganese-based hydroxide precursor is Ni x Co y Mn z (OH)₂, where x + y + z = 1, 0.20 < x ≤ 0.40; 0.00 < y ≤ 0.20; 0.60 < z ≤ 0.85; (8) The secondary particles of the lithium-rich manganese-based hydroxide precursor include a core and an outer shell layer disposed on the surface of the core, wherein the primary particle thickness of the outer shell layer is greater than the primary particle thickness of the core. (9) The oil absorption of the lithium-rich manganese-based hydroxide precursor is 50-80 mL / 100 g.

8. A positive electrode material, characterized in that, The raw materials include the lithium-rich manganese-based hydroxide precursor prepared by the method described in any one of claims 1-5.

9. A lithium-ion battery, characterized in that, Includes the cathode material as described in claim 8.

10. An electrical appliance, characterized in that, Including the lithium-ion battery as described in claim 9.

Images