A ternary precursor material, a preparation method and application thereof

Abstract

The application provides a ternary precursor material and a preparation method and application thereof. The preparation method comprises the following steps: in an inert atmosphere, metal salt solution, precipitant solution and complexing agent solution are introduced into a bottom liquid to perform nucleation reaction; after the nucleation reaction stage is completed, in an oxygen-containing atmosphere, a growth reaction is performed until product particles reach a target particle size, and reaction slurry is obtained; the reaction slurry is subjected to solid-liquid separation, and a precipitate is obtained; the precipitate is washed to obtain the ternary precursor material. The preparation method can control the pore structure of particles by controlling the atmosphere during coprecipitation, so that the impurity ions adsorbed in the particles can be quickly replaced in the washing process, thereby effectively removing sodium and sulfur impurities in the inside of the precursor particles, and the amount of washing agent can be reduced.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and relates to a ternary precursor material, its preparation method and application. Background Technology

[0002] Lithium-ion batteries possess advantages such as high energy density, high output power, high charging efficiency, and good cycle performance, making them the preferred choice for green and environmentally friendly batteries. They are mainly composed of positive electrode materials, negative electrode materials, separators, and electrolytes. The positive electrode material accounts for more than 40% of the total cost of a lithium battery and directly affects its various performance indicators. Ternary precursors are the main raw materials for synthesizing ternary positive electrode materials and directly determine the core physicochemical properties of these materials. In addition to conventional parameters such as tap density, specific surface area, and microstructure, the impurity content in the ternary precursor also significantly affects the performance of the ternary positive electrode material.

[0003] Currently, the co-precipitation method is commonly used in industry to prepare ternary precursors. The metal salt raw materials used are mostly sulfates, and the precipitant is sodium hydroxide solution. A nickel-cobalt-manganese sulfate solution, after complexing with an ammonia solution, undergoes a co-precipitation reaction with sodium hydroxide solution to form primary particles, which further agglomerate into spherical secondary particles. As the precipitation reaction proceeds, these spherical secondary particles gradually grow larger. In this synthesis reaction, a large amount of Na... + and SO4 2- It will undergo physical / chemical adsorption on the surface of the precursor and be gradually encapsulated inside the particles during the secondary particle growth process.

[0004] For precursors with smaller particle sizes, the amount of impurities adsorbed inside the particles is relatively small, and the sodium and sulfur impurities adsorbed on the particle surface and inside the particles can be removed by washing processes. Therefore, the sodium and sulfur impurity content can be basically controlled at Na≤50ppm and S≤600ppm. However, for precursors with larger particle sizes (D50>10μm), there is a greater amount of impurities adsorbed inside the particles, and these impurities are difficult to remove by washing processes. The sodium and sulfur impurity content is mostly at the level of Na≥200ppm and S≥1500ppm. These sodium and sulfur impurity ions that are not removed during the washing process can continue to be retained during the subsequent sintering process of the cathode material, resulting in a lower capacity and poorer cycle performance of the obtained ternary cathode material, which cannot meet the application requirements of power batteries.

[0005] For the removal of sodium and sulfur impurities from precursor products, industrial methods typically employ aging (alkaline soaking), hot alkali, and hot pure water stepwise washing. However, some products still exhibit excessively high impurity content even after aging and multiple washing processes. For instance, CN 112234187A discloses a method for removing sulfur and sodium from ternary precursors, which combines multi-stage washing with formamide solution soaking to remove sodium and sulfur impurities. However, formamide solution soaking may affect other properties of the product and also increases the washing process and cost.

[0006] For example, CN 112591808A discloses a method for preparing a low-sodium-sulfur nickel-cobalt-manganese ternary precursor. The method removes sodium-sulfur impurities from the precursor through multiple steps: "seed preparation - seed growth - stop reaction - increase pH - solution replacement - start reaction - particle growth to target value - stop reaction - increase pH - solution replacement - pressure filtration and washing - drying and demagnetization". However, this method involves multiple replacements of the supernatant mother liquor during the reaction process, resulting in low production efficiency. At the same time, the mother liquor contains a large amount of free nickel, which can easily disrupt the reaction equilibrium, causing the main content to deviate and the crystallinity to deteriorate. Furthermore, it cannot effectively remove sodium-sulfur impurities encapsulated inside the particles.

[0007] Based on the above research, there is a need to provide a method for preparing ternary precursor materials. This method can effectively reduce sodium and sulfur impurities in the ternary precursor materials, reduce the amount of detergent used, and does not involve mother liquor replacement, thus ensuring the crystal quality of the precursor. Summary of the Invention

[0008] The purpose of this invention is to provide a ternary precursor material, its preparation method, and its application. The preparation method controls the pore structure of the particles by controlling the atmosphere during co-precipitation, thereby allowing the adsorbed Na in the particles to... + and SO4 2- It can be quickly displaced during the washing process, thereby effectively removing sodium and sulfur impurities inside the precursor particles and reducing the amount of detergent used. It solves the problems of reduced capacity and poor cycle performance of ternary cathode materials caused by high sodium and sulfur impurity content in existing ternary precursor materials.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a ternary precursor material, the method comprising the following steps:

[0011] (1) In an inert atmosphere, a metal salt solution, a precipitant solution and a complexing agent solution are passed into the base liquid to carry out a nucleation reaction;

[0012] (2) After the nucleation reaction stage described in step (1) is completed, a growth reaction is carried out in an oxygen-containing atmosphere until the product particles reach the target particle size and a reaction slurry is obtained.

[0013] (3) The reaction slurry described in step (2) is subjected to solid-liquid separation to obtain a precipitate. The precipitate is washed to obtain the ternary precursor material.

[0014] This invention controls the oxygen content of the atmosphere in the coprecipitation reaction. The nucleation reaction is first carried out in a pure inert gas, followed by crystal growth in an oxygen-containing atmosphere. This controls the internal pore structure of the spherical particles in the product, allowing the ternary precursor material to form certain loose pores within the particles while maintaining optimized tap density and specific surface area. This facilitates the adsorption of Na during the reaction. + and SO4 2- It can be quickly displaced during the washing process, thereby effectively removing sodium and sulfur impurities inside the precursor particles, thus solving the problem that sodium and sulfur impurities cannot be removed by washing for large-particle-size ternary precursor materials.

[0015] Preferably, the pH of the nucleation reaction in step (1) is 11.0-12.8, for example, it can be 11.0, 11.2, 11.4, 11.6, 11.8, 12.0, 12.2, 12.4, 12.6 or 12.8, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] Preferably, the nucleation reaction time in step (1) is 2-8 hours, for example, it can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the metal salt solution in step (1) includes nickel ions, cobalt ions and manganese ions, wherein the concentration of the total metal ions is 1-3 mol / L, for example, it can be 1 mol / L, 2 mol / L or 3 mol / L, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0018] Preferably, the metal salt in step (1) includes a sulfate.

[0019] Preferably, in the precipitant solution of step (1), the mass fraction of the precipitant is 20-40 wt%, for example, it can be 20 wt%, 30 wt% or 40 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, in the complexing agent solution of step (1), the mass fraction of the complexing agent is 14-30 wt%, for example, it can be 14 wt%, 15 wt%, 20 wt%, 25 wt% or 30 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] Preferably, the precipitant comprises sodium hydroxide, and the complexing agent comprises ammonia.

[0022] Preferably, the pH of the base solution in step (1) is 11.0-13.0, for example, it can be 11.0, 11.5, 12.0, 12.5 or 13.0, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the base liquid in step (1) includes water, a complexing agent solution, and a precipitant solution.

[0024] In the base liquid described in this invention, the concentration of the complexing agent solution is 5-6 g / L, for example, it can be 5 g / L, 5.5 g / L or 6 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0025] Preferably, after the nucleation reaction stage described in step (1) is completed, the growth reaction stage is entered, and the pH of the system is reduced until the pH is 9.4-11.0, for example, it can be 9.4, 10.0, 10.5 or 11.0, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] This invention controls the pore structure of particles by lowering the pH, switching the nucleation and growth stages of the coprecipitation reaction, and then adjusting the oxygen content at different stages of the growth reaction, thereby avoiding affecting the tap density and specific surface area of ​​the ternary precursor material.

[0027] Preferably, the rate at which the pH of the system is reduced is no more than 0.5 per hour, for example, 0.5, 0.4, 0.3, 0.2, 0.1 or 0.05, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] Preferably, the oxygen-containing atmosphere in step (2) includes a mixture of inert gas and air.

[0029] Preferably, in the oxygen-containing atmosphere, the volume ratio of inert gas to air is (1-30):1, for example, it can be 1:1, 5:1, 10:1, 15:1, 20:1 or 30:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] The oxygen-containing atmosphere of this invention is carried out under a specific inert gas and air. If the air content is too high and the oxygen content is too high, it is easy for MnOOH or MnO2 impurity phases to appear in the precursor, causing compositional deviation and phase separation in the local structure. In addition, the primary grain stacking of the over-oxidized precursor is very loose, resulting in a low tap density and an excessively large specific surface area of ​​the precursor, all of which will affect the performance of the precursor product and the subsequent cathode material. If the air content is too low and the oxygen content is too low, sufficient and effective pore structures cannot be formed, which is not conducive to the formation of Na inside the particles. + and SO4 2- It is rapidly displaced during the washing process with dilute alkali and pure water, which fails to achieve the goal of significantly reducing sodium and sulfur impurities in the precursor.

[0031] Preferably, when the growth reaction in step (2) produces product particles with a particle size D50 of 5-8 μm, for example, 5 μm, 6 μm, 7 μm or 8 μm, the oxygen content in the oxygen-containing atmosphere in step (2) is reduced.

[0032] During the growth stage of this invention, when the particle size grows to a certain size, the oxygen content in the oxygen-containing atmosphere is adjusted to reduce the oxygen content, thereby adjusting the pore structure of the product particles. This ensures that sodium and sulfur impurities are easily washed away while ensuring that the precursor product has a sufficiently high tap density.

[0033] Preferably, after the nucleation reaction in step (1) is completed, before the particle size D50 reaches 5-8 μm, the volume ratio of inert gas to air in the oxygen-containing atmosphere is (1-20):1, for example, it can be 1:1, 5:1, 10:1, 15:1, or 20:1. During the period from the particle size D50 reaching 5-8 μm to the target particle size, the volume ratio of inert gas to air in the oxygen-containing atmosphere is (5-30):1, for example, it can be 5:1, 10:1, 15:1, 20:1, 25:1, or 30:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] In the process of reducing oxygen content, the ratio of inert gas to air can be adjusted continuously or in stages. The oxygen content can be maintained at two or more stepped plateaus, so that the degree of oxidation in the later stage of growth is lower than that in the early stage of growth.

[0035] Preferably, the D50 of the target particle size in step (2) is 10 μm or more, for example, it can be 10 μm, 12 μm, 14 μm, 16 μm, 18 μm or 20 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] The preparation method described in this invention is preferably designed for large-particle-size ternary precursor materials. Since sodium and sulfur impurities in large-particle-size ternary precursor materials are not easily washed away, the method of this invention can effectively reduce the content of sodium ions and sulfate ions.

[0037] Preferably, the reaction system temperatures in steps (1) and (2) are independently 40-70°C, for example, 40°C, 50°C, 60°C or 70°C, and the concentration of the complexing agent is 2-13 g / L, for example, 2 g / L, 5 g / L, 10 g / L or 13 g / L, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, the washing liquid in step (3) includes alkaline solution and pure water.

[0039] This invention uses alkaline solution and pure water to wash the product more than twice, with the alkaline solution washing performed first, followed by pure water washing.

[0040] Preferably, the temperature of the alkaline solution is 50-80°C, for example, 50°C, 60°C, 70°C or 80°C, and the temperature of the pure water is 50-80°C, for example, 50°C, 60°C, 70°C or 80°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the alkaline solution comprises any one or a combination of at least two of sodium hydroxide, sodium carbonate, or sodium bicarbonate.

[0042] Preferably, the mass fraction of the alkali solution is 2-10 wt%, for example, it can be 2 wt%, 4 wt%, 6 wt%, 8 wt% or 10 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, step (3) further includes a drying step after washing, wherein the drying temperature is 80-150℃, for example, it can be 80℃, 100℃, 120℃, 140℃ or 150℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0044] Preferably, the moisture content of the dried material obtained by drying is 0.1-1.0 wt%, for example, it can be 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.7 wt%, 0.9 wt% or 1.0 wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] As a preferred embodiment of the preparation method of the present invention, the preparation method includes the following steps:

[0046] (1) In an inert atmosphere, a metal salt solution, a precipitant solution and a complexing agent solution are passed into a base liquid to carry out a nucleation reaction. The pH of the nucleation reaction is 11.0-12.8 and the time is 2-8 hours.

[0047] The metal salt solution includes sulfates, and the total metal ion concentration is 1-3 mol / L;

[0048] The pH of the underlying solution is 11.0-13.0, and it includes water, a complexing agent solution, and a precipitant solution.

[0049] (2) After the nucleation reaction stage described in step (1) is completed, the pH of the system is reduced, and the growth reaction is carried out in a mixed atmosphere with an inert gas and air volume ratio of (1-20):1. When the particle size D50 of the product particles is 5-8 μm, the oxygen content in the mixed atmosphere is reduced so that the volume ratio of inert gas and air is (5-30):1. Then the reaction continues until the product particles reach the target particle size D50 of more than 10 μm to obtain the reaction slurry.

[0050] The rate at which the pH of the system is reduced is no more than 0.5 per hour until the pH drops to 9.4-11.0;

[0051] The reaction system temperatures in steps (1) and (2) are independently 40-70℃, and the concentration of the complexing agent is 2-13 g / L;

[0052] (3) The reaction slurry described in step (2) is subjected to solid-liquid separation to obtain a precipitate. The precipitate is washed with alkaline solution and pure water, wherein the temperature of the alkaline solution is 50-80℃ and the temperature of the pure water is 50-80℃. Then it is dried at 80-150℃ until the moisture content of the dried material is 0.1-1.0wt%, thereby obtaining the ternary precursor material.

[0053] In a second aspect, the present invention provides a ternary precursor material prepared by the preparation method described in the first aspect, wherein the particle size D50 of the ternary precursor material is ≥10μm, for example, it can be 10μm, 12μm, 14μm, 16μm, 18μm or 20μm, the content of sodium impurity is ≤100ppm, for example, it can be 100ppm, 80ppm, 60ppm, 40ppm or 20ppm, and the content of sulfur impurity is ≤800ppm, for example, it can be 800ppm, 700ppm, 600ppm, 500ppm, 400ppm or 300ppm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0054] Thirdly, the present invention provides a cathode material, wherein the raw materials for preparing the cathode material include the ternary precursor material as described in the second aspect.

[0055] Fourthly, the present invention provides a battery comprising the positive electrode material as described in the third aspect.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] This invention controls the pore structure of particles by controlling the atmosphere during co-precipitation, thereby controlling the adsorption of Na within the particles. + and SO4 2- It can be quickly displaced during the washing process, thereby effectively removing sodium and sulfur impurities inside the precursor particles and reducing the amount of detergent used. It solves the problems of reduced capacity and poor cycle performance of ternary cathode materials caused by high sodium and sulfur impurity content in existing ternary precursor materials. Attached Figure Description

[0058] Figure 1 The graph shows the change of reaction conditions over reaction time in Example 1.

[0059] Figure 2 The X-ray diffraction pattern of the ternary precursor material obtained in Example 1 is shown.

[0060] Figure 3 The X-ray diffraction pattern of the ternary precursor material obtained in Example 4 is shown. Detailed Implementation

[0061] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0062] Example 1

[0063] This embodiment provides a method for preparing a ternary precursor material, the method comprising the following steps:

[0064] (1) In nitrogen, a metal salt solution, a sodium hydroxide solution and ammonia water are introduced into a reactor containing a bottom liquid in parallel to carry out a nucleation reaction. The pH of the nucleation reaction is 11.8±0.05 and the time is 4h.

[0065] The metal salt solution is based on the molecular formula Ni 0.8 Co 0.1 Mn 0.1 A mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate with a total metal ion concentration of 2 mol / L was prepared by dispersing the metal ions in (OH)2; the sodium hydroxide solution had a mass fraction of 32 wt%, and the ammonia solution had a mass fraction of 16 wt%.

[0066] The pH of the base solution is 11.8±0.05, and it includes water, ammonia and sodium hydroxide solution, with the concentration of ammonia being 5.5 g / L.

[0067] (2) After the nucleation reaction stage described in step (1) is completed, the pH of the system is reduced, and the growth reaction is carried out in a mixed atmosphere with a nitrogen and air volume ratio of 3:1. When the particle size D50 of the product particles is 6μm, the oxygen content in the mixed atmosphere is reduced to make the nitrogen and air volume ratio 8:1. Then the reaction continues until the product particles reach a particle size D50 of 13μm to obtain the reaction slurry.

[0068] The pH of the system is reduced at a rate of 0.1 per hour until the pH drops to 10.5, and the pH value during the growth phase is controlled within the range of 10.50 ± 0.10.

[0069] The graph shows the changes in reaction conditions for the coprecipitation reaction in steps (1) and (2) over time. Figure 1 As shown, the reaction conditions include pH value, oxygen content in the atmosphere and particle size D50 of the product; the system temperature in steps (1) and (2) is 60℃, and the concentration of ammonia water is 5.5±0.5g / L, respectively.

[0070] (3) After the reaction slurry described in step (2) is allowed to settle, the supernatant is extracted, the remaining material is pumped into a centrifuge, an alkaline solution is added, and the material is washed twice with alkaline solution. Then, the alkaline-washed material is washed four times with hot water, wherein the alkaline solution is a sodium hydroxide solution with a mass fraction of 5 wt% at a temperature of 70°C, and the pure water is at a temperature of 70°C. The washed material is then dried at 100°C until the moisture content of the dried material is 0.5 wt%. The ternary precursor material is obtained by sieving and demagnetizing. The X-ray diffraction pattern of the ternary precursor material is shown below. Figure 2 As shown.

[0071] Example 2

[0072] This embodiment provides a method for preparing a ternary precursor material, the method comprising the following steps:

[0073] (1) In nitrogen, a metal salt solution, a sodium hydroxide solution and ammonia water are passed into the base liquid to carry out a nucleation reaction. The pH of the nucleation reaction is 11.0 and the time is 5h.

[0074] The metal salt solution is based on the molecular formula Ni 0.8 Co 0.1 Mn 0.1A mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate with a total metal ion concentration of 1 mol / L was prepared by dispersing the metal ions in (OH)2; the sodium hydroxide solution had a mass fraction of 20 wt%, and the ammonia solution had a mass fraction of 14 wt%.

[0075] The pH of the base solution is 11.0, and it includes water, ammonia, and sodium hydroxide solution, with the concentration of ammonia being 5 g / L.

[0076] (2) After the nucleation reaction stage described in step (1) is completed, the pH of the system is reduced, and the growth reaction is carried out in a mixed atmosphere with a nitrogen and air volume ratio of 1:1 until the particle size D50 of the product particles is 5 μm. Then, the oxygen content in the mixed atmosphere is reduced so that the nitrogen and air volume ratio is 5:1. The reaction continues until the product particles reach the target particle size D50 of 10 μm to obtain the reaction slurry.

[0077] The pH of the system is reduced at a rate of 0.2 per hour until the pH drops to 9.4;

[0078] The reaction system temperatures in steps (1) and (2) are independently 70°C, and the concentration of ammonia is 2 g / L.

[0079] (3) After the reaction slurry described in step (2) is allowed to settle, the supernatant is extracted, the remaining material is pumped into a centrifuge, an alkaline solution is added, and the material is washed twice with alkaline solution. Then, the material after alkaline washing is washed with pure water. The alkaline solution is a sodium hydroxide solution with a temperature of 50°C and a mass fraction of 10wt%, and the pure water is at a temperature of 50°C. The material after water washing is then dried at 150°C until the moisture content of the dried material is 0.1wt%. The ternary precursor material is obtained by sieving and demagnetizing.

[0080] Example 3

[0081] This embodiment provides a method for preparing a ternary precursor material, the method comprising the following steps:

[0082] (1) In nitrogen, a metal salt solution, a sodium hydroxide solution and ammonia water are passed into the base liquid to carry out a nucleation reaction. The pH of the nucleation reaction is 12.8 and the time is 3 hours.

[0083] The metal salt solution is based on the molecular formula Ni 0.8 Co 0.1 Mn 0.1 A mixed solution of nickel sulfate, cobalt sulfate, and manganese sulfate with a total metal ion concentration of 3 mol / L was prepared by dispersing the metal ions in (OH)2; the sodium hydroxide solution had a mass fraction of 40 wt%, and the ammonia solution had a mass fraction of 30 wt%.

[0084] The bottom solution has a pH of 13.0 and includes water, ammonia, and sodium hydroxide solution, with the ammonia concentration being 6 g / L.

[0085] (2) After the nucleation reaction stage described in step (1) is completed, the pH of the system is reduced, and the growth reaction is carried out in a mixed atmosphere with a nitrogen and air volume ratio of 20:1. When the particle size D50 of the product particles is 8 μm, the oxygen content in the mixed atmosphere is reduced to a nitrogen and air volume ratio of 30:1. The reaction is then continued until the product particles reach the target particle size D50 of 15 μm to obtain the reaction slurry.

[0086] The pH of the system is reduced at a rate of 0.1 per hour until the pH drops to 11.0;

[0087] The reaction system temperatures in steps (1) and (2) were independently 40°C, and the concentration of ammonia was 13 g / L.

[0088] (3) After the reaction slurry described in step (2) is allowed to settle, the supernatant is extracted, the remaining material is pumped into a centrifuge, an alkaline solution is added, and the material is washed twice with alkaline solution. Then, the material after alkaline washing is washed with pure water. The alkaline solution is a sodium hydroxide solution with a temperature of 80°C and a mass fraction of 2wt%, and the pure water is at a temperature of 80°C. The material after water washing is then dried at 80°C until the moisture content of the dried material is 1.0wt%. The ternary precursor material is obtained by sieving and demagnetizing.

[0089] Example 4

[0090] This embodiment provides a method for preparing a ternary precursor material. Except for step (2), where the particle size D50 of the product particles reaches 6 μm and the volume ratio of nitrogen to air is 0.5:1, the preparation method is the same as in Example 1.

[0091] The X-ray diffraction pattern of the ternary precursor material obtained in this embodiment is as follows: Figure 3 As shown.

[0092] Example 5

[0093] This embodiment provides a method for preparing a ternary precursor material. Except for step (2) where the particle size D50 of the product particles reaches 6 μm and the volume ratio of nitrogen to air is 22:1, the preparation method is the same as in Example 1.

[0094] Example 6

[0095] This embodiment provides a method for preparing a ternary precursor material. Except that after the particle size D50 of the product particles in step (2) reaches 6 μm, the oxygen content in the mixed atmosphere is not reduced, and the reaction continues at a nitrogen to air volume ratio of 3:1, the rest of the preparation method is the same as in Example 1.

[0096] Example 7

[0097] This embodiment provides a method for preparing a ternary precursor material. Except for step (2), when the particle size D50 of the product particles reaches 6 μm, the oxygen content in the mixed atmosphere is adjusted so that the volume ratio of nitrogen to air is 32:1. The rest of the preparation method is the same as in Example 1.

[0098] Example 8

[0099] This embodiment provides a method for preparing a ternary precursor material. Except for step (2), when the particle size D50 of the product particles reaches 6 μm, the preparation method is the same as in Example 1.

[0100] Comparative Example 1

[0101] This comparative example provides a method for preparing a ternary precursor material. Except for step (2), which is carried out under pure nitrogen conditions, the preparation method is the same as that in Example 1.

[0102] Comparative Example 2

[0103] This comparative example provides a method for preparing a ternary precursor material. Except for step (1), in which the reaction is carried out at a nitrogen to air volume ratio of 3:1, the preparation method is the same as that in Example 1.

[0104] The contents of Na and S in the materials after the reaction was stopped at the end of step (2), the first alkaline wash, the second alkaline wash, the first hot water wash, the second hot water wash, the third hot water wash, the fourth hot water wash, and the drying in the above embodiments and comparative examples, as well as the particle size D50, compaction density, and specific surface area of ​​the ternary precursor materials are shown in Tables 1, 2, and 3.

[0105] Table 1

[0106]

[0107] Table 2

[0108]

[0109] Table 3

[0110] Particle size D50 (μm) <![CDATA[Compaction density (g / cm 3 )]]> <![CDATA[Specific surface area BET (m 2 / g)]]> Example 1 13.04 1.936 9.16 Example 2 10.14 1.808 10.22 Example 3 15.02 2.024 8.74 Example 4 13.06 1.553 12.33 Example 5 13.07 1.949 8.95 Example 6 13.04 1.684 11.20 Example 7 13.09 1.958 9.01 Example 8 13.02 1.975 8.90 Comparative Example 1 13.03 2.012 8.84 Comparative Example 2 13.05 1.659 11.41

[0111] As can be seen from Table 1:

[0112] The ternary precursor material obtained by this invention has a particle size D50 ≥ 10 μm, a sodium impurity content ≤ 100 ppm, a sulfur impurity content ≤ 800 ppm, and a compaction density ≥ 1.8 g / cm³. 3 Specific surface area is 6-12 m² 2 / g; As can be seen from Example 1 and Comparative Examples 1-2, when the nucleation and growth stages of the coprecipitation reaction are carried out using pure nitrogen or oxygen-containing atmosphere, it is impossible to simultaneously ensure that the ternary precursor has a low impurity content and a high compaction density; As can be seen from Example 1 and Examples 4-8, the atmosphere in the growth stage of step (2) will affect the impurity content, compaction density and specific surface area of ​​the ternary precursor material. The atmosphere of the present invention can further ensure the tap density and specific surface area while making Na + and SO4 2- It is rapidly displaced during the washing process, thereby effectively removing sodium and sulfur impurities from inside the precursor particles.

[0113] In summary, this invention provides a ternary precursor material, its preparation method, and its application. The preparation method controls the pore structure of the particles by controlling the atmosphere during co-precipitation, thereby allowing the adsorbed Na in the particles to... + and SO4 2- It can be quickly displaced during the washing process, thereby effectively removing sodium and sulfur impurities inside the precursor particles and reducing the amount of detergent used. It solves the problems of reduced capacity and poor cycle performance of ternary cathode materials caused by high sodium and sulfur impurity content in existing ternary precursor materials.

[0114] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a ternary precursor material, characterized in that, The preparation method includes the following steps: (1) In an inert atmosphere, a metal salt solution, a precipitant solution and a complexing agent solution are passed into the base liquid to carry out a nucleation reaction; (2) After the nucleation reaction stage described in step (1) is completed, a growth reaction is carried out in an oxygen-containing atmosphere until the product particles reach the target particle size and a reaction slurry is obtained. When the growth reaction in step (2) reaches a particle size D50 of 5-8 μm, reduce the oxygen content in the oxygen-containing atmosphere in step (2). After the nucleation reaction in step (1) is completed, before the particle size D50 reaches 5-8 μm, the volume ratio of inert gas to air in the oxygen-containing atmosphere is (1-20):

1. During the period from the particle size D50 reaching 5-8 μm to the target particle size, the volume ratio of inert gas to air in the oxygen-containing atmosphere is (5-30):

1. (3) The reaction slurry described in step (2) is subjected to solid-liquid separation to obtain a precipitate. The precipitate is then washed to obtain the ternary precursor material.

2. The preparation method according to claim 1, characterized in that, The pH of the nucleation reaction in step (1) is 11.0-12.

8.

3. The preparation method according to claim 1, characterized in that, The nucleation reaction in step (1) takes 2-8 hours.

4. The preparation method according to claim 1, characterized in that, The metal salt solution in step (1) includes nickel ions, cobalt ions and manganese ions, wherein the total concentration of metal ions is 1-3 mol / L.

5. The preparation method according to claim 1, characterized in that, The metal salt in step (1) includes sulfates.

6. The preparation method according to claim 1 or 2, characterized in that, In step (1), the mass fraction of the precipitant in the precipitant solution is 20-40 wt%.

7. The preparation method according to claim 1, characterized in that, In step (1), the complexing agent solution contains a mass fraction of 14-30 wt% complexing agent.

8. The preparation method according to claim 1, characterized in that, The pH of the base solution in step (1) is 11.0-13.

0.

9. The preparation method according to claim 1, characterized in that, The base liquid in step (1) includes water, a complexing agent solution, and a precipitant solution.

10. The preparation method according to any one of claims 1-3, characterized in that, After the nucleation reaction stage described in step (1) is completed, the growth reaction stage begins, and the pH of the system is reduced until the pH is 9.4-11.

0.

11. The preparation method according to claim 10, characterized in that, The rate at which the pH of the system is reduced is no more than 0.5 per hour.

12. The preparation method according to claim 1, characterized in that, The target particle size in step (2) has a D50 of 10 μm or more.

13. The preparation method according to claim 1, characterized in that, The reaction system temperatures in steps (1) and (2) are independently 40-70℃, and the concentration of the complexing agent is 2-13g / L.

14. The preparation method according to claim 1, characterized in that, The washing liquid used in step (3) includes alkaline solution and pure water.

15. The preparation method according to claim 14, characterized in that, The temperature of the alkaline solution is 50-80℃, and the temperature of the pure water is 50-80℃.

16. The preparation method according to claim 14, characterized in that, The alkaline solution includes any one or a combination of at least two of sodium hydroxide, sodium carbonate, or sodium bicarbonate.

17. The preparation method according to claim 14, characterized in that, The mass fraction of the alkaline solution is 2-10 wt%.

18. The preparation method according to claim 1, characterized in that, Step (3) includes a drying step after washing, wherein the drying temperature is 80-150℃.

19. The preparation method according to claim 18, characterized in that, The moisture content of the dried material obtained by the drying process is 0.1-1.0 wt%.

20. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) In an inert atmosphere, a metal salt solution, a precipitant solution and a complexing agent solution are passed into the bottom liquid to carry out a nucleation reaction. The pH of the nucleation reaction is 11.0-12.8 and the time is 2-8h. The metal salt solution includes sulfates, and the total metal ion concentration is 1-3 mol / L; The pH of the underlying solution is 11.0-13.0, and it includes water, a complexing agent solution, and a precipitant solution. (2) After the nucleation reaction stage described in step (1) is completed, the pH of the system is reduced, and the growth reaction is carried out in a mixed atmosphere with an inert gas and air volume ratio of (1-20):

1. When the particle size D50 of the product particles is 5-8 μm, the oxygen content in the mixed atmosphere is reduced so that the volume ratio of inert gas and air is (5-30):

1. Then the reaction continues until the product particles reach the target particle size D50 of more than 10 μm to obtain the reaction slurry. The rate at which the pH of the system is reduced is no more than 0.5 per hour, until the pH drops to 9.4-11.0; The reaction system temperatures in steps (1) and (2) are independently 40-70℃, and the concentration of the complexing agent is 2-13 g / L; (3) The reaction slurry described in step (2) is subjected to solid-liquid separation to obtain a precipitate. The precipitate is washed with alkaline solution and pure water, wherein the temperature of the alkaline solution is 50-80℃ and the temperature of the pure water is 50-80℃. Then it is dried at 80-150℃ until the moisture content of the dried material is 0.1-1.0wt%, thus obtaining the ternary precursor material.

21. A ternary precursor material prepared by the preparation method according to any one of claims 1-20, characterized in that, The ternary precursor material has a particle size D50 ≥ 10 μm, a sodium impurity content ≤ 100 ppm, and a sulfur impurity content ≤ 800 ppm.

22. A positive electrode material, characterized in that, The raw materials for preparing the cathode material include the ternary precursor material as described in claim 21.

23. A battery, characterized in that, The battery includes the positive electrode material as described in claim 22.

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