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CN-122010194-A - Directional crystallization process of high-nickel ternary precursor

CN122010194ACN 122010194 ACN122010194 ACN 122010194ACN-122010194-A

Abstract

The invention discloses a directional crystallization process of a high-nickel ternary precursor in the technical field of inorganic functional materials, which comprises the steps of dispersing a modifier in a base solution containing ammonia water under an inert atmosphere to form a suspension, performing explosive nucleation at a high feeding rate, converting the crystal nuclei into steady-state growth after reaching a target size, maintaining a constant acid-base number by precisely controlling acid-base feeding, guiding the radial ordered deposition of metal hydroxide by utilizing the crystal face guiding action of the modifier, and finally aging, washing and drying to obtain the high-nickel ternary precursor. The modifier is prepared by performing solvothermal synthesis, protecting and calcining in a lithium carbonate atmosphere to obtain a cubic phase nano-core, coating a titanium dioxide shell layer by using low-temperature sol-gel, crystallizing, and finally treating an activated surface by using dilute ammonia water. The precursor prepared by the process has the advantages of uniform components, radial arrangement of primary particles, high sphericity and narrow particle size distribution, and the electrochemical performance of the precursor is effectively improved.

Inventors

  • WANG LINGYUN
  • WANG XIAOPEI
  • CHEN JIANFENG

Assignees

  • 怀化炯诚新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260209

Claims (10)

  1. 1. The directional crystallization process of the high-nickel ternary precursor is characterized by comprising the following steps of: s1, adding deionized water into a reaction kettle in parts by weight, stirring, heating to 54.5-55.5 ℃, introducing nitrogen, adding a lithium zirconate titanate lanthanum-based heterostructure crystal face modifier, shearing and dispersing, and pumping concentrated ammonia water to enable the ammonia concentration to reach 4.0-6.0g/L to obtain a suspension; S2, starting a feeding pump of a metal salt solution containing nickel sulfate, cobalt sulfate and manganese sulfate, a sodium hydroxide solution and ammonia water, increasing the feeding rate of the metal salt solution containing nickel sulfate, cobalt sulfate and manganese sulfate and the sodium hydroxide solution by 2-4 times of the feeding rate of a steady-state growth stage in the initial 3-5min, adjusting the feeding rate of the ammonia water to 40-60% of the feeding rate of the steady-state growth stage, and switching to the next stage when the particle D50 reaches a target value by monitoring through an online particle sizer; S3, reducing the feeding rates of a metal salt solution containing nickel sulfate, cobalt sulfate, manganese sulfate, a sodium hydroxide solution and ammonia water to the feeding rate in a steady-state growth stage, starting an automatic feedback control system to adjust the pH value to 11.28-11.32, and adjusting the feeding rates of alkali liquor and ammonia water in a linkage manner; s4, stopping feeding after the target granularity is reached, stirring and aging to obtain slurry, transferring the slurry to filtering equipment, washing with hot deionized water at 60-80 ℃, and finally drying in a vacuum drying oven at 118-122 ℃.
  2. 2. The process for the directional crystallization of a high nickel ternary precursor according to claim 1, wherein in step S1, the time for shearing and dispersing is 10 to 15min.
  3. 3. The process for the directional crystallization of a high nickel ternary precursor according to claim 1, wherein in step S2, the target value is 1.4-1.6 μm.
  4. 4. The process for the directional crystallization of a high nickel ternary precursor according to claim 1, wherein in step S3, the time for guiding the metal hydroxide to grow in radial order deposition is 20 to 40 hours.
  5. 5. The process for the directional crystallization of a high nickel ternary precursor according to claim 1, wherein in step S4, the drying time in a vacuum drying oven at 118-122 ℃ is 12-14h.
  6. 6. The directional crystallization process of a high nickel ternary precursor according to any one of claims 1 to 5, wherein the preparation step of the lithium lanthanum zirconate titanate based heterostructure crystal plane modifier comprises: Dissolving lithium nitrate, lanthanum nitrate, zirconium oxychloride and tantalum ethoxide in a mixed solvent of ethylene glycol and absolute ethyl alcohol in parts by weight, stirring, dropwise adding citric acid, regulating the pH to 8-9 by using ammonia water, transferring into a high-pressure reaction kettle, performing solvothermal reaction at 218-222 ℃, centrifuging after cooling, collecting precipitate, alternately washing the precipitate by using 60-80 ℃ deionized water and absolute ethyl alcohol, and performing vacuum drying at 78-82 ℃ to obtain precursor powder, paving the precursor powder in a crucible containing lithium carbonate powder, then calcining at 895-905 ℃ in air atmosphere, performing high-energy ball milling in an ethanol medium after cooling to obtain LLZTO nano powder; Dispersing LLZTO nanometer powder in absolute ethyl alcohol, carrying out ultrasonic treatment to obtain LLZTO ethanol suspension, dripping tetraisopropyl titanate into a mixed solution of absolute ethyl alcohol and glacial acetic acid, stirring to obtain titanium sol, dripping LLZTO ethanol suspension into the titanium sol under the protection of nitrogen, at 0-10 ℃ and with stirring, aging, centrifuging to obtain composite powder coated with an amorphous titanium layer, and centrifugally washing the composite powder coated with the amorphous titanium layer with 0-10 ℃ absolute ethyl alcohol to obtain washed composite powder; a3, placing the washed composite powder in a muffle furnace, performing heat treatment at 295-305 ℃ in an air atmosphere, and then heating to 595-605 ℃ for heat treatment to obtain LLZTO@titanium dioxide composite nano particles; A4, dispersing the LLZTO@titanium dioxide composite nano particles in a dilute ammonia water solution, carrying out ultrasonic treatment at 30-40 ℃, carrying out centrifugal separation to obtain a solid product, washing the solid product with water and ethanol, and drying.
  7. 7. The process for the directional crystallization of a high nickel ternary precursor according to claim 6, wherein in step A1, the calcination time at a temperature of 895-905 ℃ is 6-8h.
  8. 8. The process for the directional crystallization of a high nickel ternary precursor according to claim 6, wherein in step A2, the aging time is 12 to 14 hours.
  9. 9. The process for the directional crystallization of a high nickel ternary precursor according to claim 6, wherein in the step A3, the heat treatment is performed for a period of 4 to 6 hours at a temperature of 595 to 605 ℃.
  10. 10. The process for the directional crystallization of a high nickel ternary precursor according to claim 6, wherein in step A4, the time of the ultrasonic treatment at 30-40 ℃ is 30-60min.

Description

Directional crystallization process of high-nickel ternary precursor Technical Field The invention relates to the technical field of inorganic functional materials, in particular to a directional crystallization process of a high-nickel ternary precursor. Background The high-nickel ternary positive electrode material is used as a core component of a next-generation high-energy-density lithium ion battery, and the performance quality of the high-nickel ternary positive electrode material is directly related to the endurance mileage, the safety reliability and the service life of the battery. The performance of the material in practical application basically depends on the microstructure and physicochemical properties of the precursor. The ideal precursor should have a precisely controllable stoichiometric ratio, extremely high compositional uniformity, a regular dense spherical morphology, and a suitable particle size distribution. The orientation arrangement of the primary particles in the secondary spheres, namely whether crystals can grow orderly along a specific direction, has a critical influence on the lithium ion diffusion kinetics, mechanical structure stability and cycle life of the final sintered product. Therefore, how to realize the precise regulation and control of the multi-stage structure from the atomic scale to the micro morphology of the high-nickel ternary precursor by optimizing the preparation process becomes one of the key technical challenges of overcoming the contradiction between the energy density and the stability in the current lithium battery material field. Currently, hydroxide coprecipitation methods are commonly used in industry and academia to prepare such precursors. The method comprises the steps of adding mixed metal salt solution, precipitant and complexing agent in a reaction system in parallel flow, and precipitating out metal ions under constant conditions. However, this conventional path faces several inherent bottlenecks. Firstly, due to the obvious difference between the precipitation dissolution equilibrium constants and the complexation stability constants of nickel, cobalt, manganese and other different metal ions, in a complex reaction environment with high concentration, high viscosity and strong stirring, synchronous precipitation at a completely uniform speed is extremely difficult to realize, and the segregation of components of the product on the nanometer and even atomic scale is extremely easy to cause. Secondly, the control of the crystallization process by the conventional process is relatively extensive, and the nucleation and growth phases are often mutually interweaved and interfered, so that the nucleation and growth phases are difficult to separate. This generally results in uncontrollable nucleation numbers and non-uniform crystal nucleus sizes, and in the subsequent growth stage, ostwald ripening is easily occurred, i.e. small particles dissolve and large particles continue to grow up, eventually widening the particle size distribution of the precursor particles and irregular morphology. More importantly, the traditional method lacks the capability of guiding the crystal growth direction, and the obtained primary particles are stacked in random orientation, so that anisotropic stress accumulation and microcracks are more easily generated in the repeated charge and discharge processes of the battery, and the acceleration performance is attenuated. In response to the above problems, researchers have tried various improvement strategies such as optimizing the reactor structure, finely controlling the ph and feed rate, introducing special additives or seeds, etc. However, these improvements have mostly focused on tuning of macroscopic process parameters, or can only improve on certain single performance metrics. For example, simple additives may affect particle size but not contribute to component uniformity, and complex post-treatments increase cost and may destroy structure. Especially, a systematic scheme which can start from the source of crystallography and solve three problems of component uniformity, morphology regularity and crystal orientation is lacking. Therefore, a brand new preparation process capable of guiding the directional growth of crystals internally and a high-efficiency modifier matched with the preparation process are developed, and precursors with radial ordered microstructures are directly constructed in the precipitation process through a physical and chemical means, so that the preparation process becomes a necessary way for breaking through the bottleneck of the prior art and obtaining high-performance products. The method not only can improve the intrinsic characteristics of the material, but also has important practical significance for promoting the industrialized development of the high-end lithium ion battery. Disclosure of Invention The invention aims to provide a directional crystallization process of a high-nickel