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CN-121990616-A - High-nickel positive electrode material and preparation method thereof

CN121990616ACN 121990616 ACN121990616 ACN 121990616ACN-121990616-A

Abstract

The invention belongs to the technical field of positive electrode materials, and particularly relates to a high-nickel positive electrode material and a preparation method thereof. The invention aims to solve the problem that the cycle life and the energy density of the existing high-nickel positive electrode material are difficult to achieve. The method comprises the steps of dissolving nickel sulfate, cobalt sulfate and manganese sulfate in water to prepare a metal salt solution, adding an internal doping agent, introducing a base solution into a reaction kettle under the protection of nitrogen, regulating the pH value and the ammonia concentration, adding the metal salt solution, a precipitant and a complexing agent in parallel, controlling the pH value and the free ammonia concentration of a system to react, then linearly reducing the pH value and the free ammonia concentration, stopping feeding and aging treatment, centrifugally washing and vacuum drying a solid product to obtain a spherical precursor, mixing the spherical precursor with lithium hydroxide, adding tungsten trioxide powder, sintering in an oxygen atmosphere, annealing at constant temperature in the nitrogen atmosphere, and flash annealing after washing to obtain the high-nickel anode material.

Inventors

  • WU KANGLE
  • FAN ZHAOFENG
  • LIANG CHAO

Assignees

  • 扬州虹途电子材料有限公司
  • 扬州虹一新材料有限公司

Dates

Publication Date
20260508
Application Date
20260209

Claims (8)

  1. 1. A preparation method of a high-nickel positive electrode material is characterized by comprising the following steps: Dissolving nickel sulfate, cobalt sulfate and manganese sulfate in water to prepare a metal salt solution, and adding an internal doping agent; introducing base solution into the reaction kettle under the protection of nitrogen, adjusting the pH value and the ammonia concentration, and entering a precursor synthesis stage; the precursor synthesis stage comprises the steps of adding the metal salt solution into the base solution in parallel flow, adding a precipitator and a complexing agent, controlling the pH value of the system and the concentration of free ammonia to react, then linearly reducing the pH value and the concentration of the free ammonia, stopping feeding and aging treatment, and centrifugally washing and vacuum drying a solid product to obtain a spherical precursor; Mixing the spherical precursor with lithium hydroxide, adding tungsten trioxide powder, sintering in oxygen atmosphere, and annealing at constant temperature in nitrogen atmosphere to obtain electrode material; And cleaning the electrode material by using a buffer cleaning solution, and then carrying out flash annealing to obtain the high-nickel anode material.
  2. 2. The method for preparing a high-nickel positive electrode material according to claim 1, wherein the molar ratio of nickel sulfate, cobalt sulfate and manganese sulfate in the metal salt solution is 83:11:5, and the internal dopant is chromium nitrate nonahydrate.
  3. 3. The preparation method of the high-nickel anode material according to claim 1, wherein in the precursor synthesis stage, a precipitant is sodium hydroxide solution, a complexing agent is ammonia water solution, the pH value of a system controlled in the reaction stage is between 11.2 and 11.6, the concentration of free ammonia in a reaction kettle is between 0.58 and 0.63mol/L, and the reaction lasts for 5 hours.
  4. 4. The method of claim 1, wherein the precursor synthesis step is performed by linearly decreasing the pH to 10.5 within 15 hours and stopping the feed after linearly decreasing the free ammonia concentration to 0.35 mol/L.
  5. 5. The method for preparing a high-nickel cathode material according to claim 1, wherein the ratio of the total molar amount of other metal elements to the molar amount of lithium element in the mixing process of the spherical precursor and lithium hydroxide is 55:68-77, the sintering temperature in the oxygen atmosphere is 780 ℃, and the constant-temperature annealing temperature in the nitrogen atmosphere is 450 ℃.
  6. 6. The method for preparing a high nickel anode material according to claim 1, wherein the buffer cleaning solution is an aqueous solution of monoammonium phosphate, and the buffer pH value is in the range of 6.0-6.5.
  7. 7. The method for preparing a high nickel anode material according to claim 1, wherein the flash annealing is performed at a temperature of 400-430 ℃ in air.
  8. 8. A high-nickel positive electrode material is characterized in that the high-nickel positive electrode material is prepared by the preparation method of any one of claims 1-7.

Description

High-nickel positive electrode material and preparation method thereof Technical Field The invention belongs to the technical field of positive electrode materials, and particularly relates to a high-nickel positive electrode material and a preparation method thereof. Background Lithium ion batteries have become a central power source for global electric vehicles and large-scale energy storage systems by virtue of their high energy density and long cycle life. As a decisive component of the electrochemical performance of the battery, the positive electrode material not only occupies more than 40% of the cell cost, but its crystal structure stability is more directly related to the upper limit of the energy density of the battery and the risk of thermal runaway. With the continuous rising of the demands of the market for endurance mileage, the multi-electron redox capability provided by the nickel element of the high-nickel layered oxide becomes a technical route for realizing high specific capacity. However, existing high nickel material systems are facing serious physicochemical challenges in terms of ultimate performance development. Nickel ions are strong active ions, and during the charge and discharge process, the change of electron orbit configuration can lead to the distortion of oxygen octahedron along the axial direction. As the lithium removal depth increases, this microscopic lattice distortion can accumulate as macroscopic anisotropic volume changes, resulting in microcracking inside the particles. These cracks not only cut off the electron transport path, but also provide channels for the penetration of electrolyte, exacerbating side reactions. Since the ionic radii of divalent nickel ions and lithium ions are very close, divalent nickel ions are very likely to migrate to lithium layer sites during high temperature synthesis or cycling. The mixed discharge effect blocks a two-dimensional diffusion channel of lithium ions, and the multiplying power performance of the material is obviously reduced. At the same time, the surface of the high nickel material tends to react with water and carbon dioxide in the air to produce lithium hydroxide and lithium carbonate residues. This not only increases the risk of gelation during battery pulping, but also tends to induce flatulence at high temperatures and pressures. In the prior art, a chromium doping mode and the like are generally used for stabilizing the lattice structure of the high-nickel positive electrode material, but in the conventional high-temperature solid-phase sintering process, the control of process conditions is difficult, and the distribution condition of chromium element can obviously influence the comprehensive performance of the electrode, so that the contradiction of difficult reconciliation exists among the cycle life, the safety and the energy density of the high-nickel electrode. In order to solve the problem that the cycle life and the energy density of the existing high-nickel positive electrode material are difficult to achieve, the high-nickel positive electrode material and the preparation method thereof are provided. Disclosure of Invention The invention aims to provide a high-nickel positive electrode material and a preparation method thereof. The method comprises the steps of dissolving nickel sulfate, cobalt sulfate and manganese sulfate in water to prepare a metal salt solution, adding an internal doping agent, introducing a base solution into a reaction kettle under the protection of nitrogen, regulating the pH value and the ammonia concentration, adding the metal salt solution, a precipitant and a complexing agent in parallel, controlling the pH value and the free ammonia concentration of a system to react, then linearly reducing the pH value and the free ammonia concentration, stopping feeding and aging treatment, centrifugally washing and vacuum drying a solid product to obtain a spherical precursor, mixing the spherical precursor with lithium hydroxide, adding tungsten trioxide powder, sintering in an oxygen atmosphere, annealing at constant temperature in the nitrogen atmosphere, and flash annealing after washing to obtain the high-nickel anode material. In order to achieve the above purpose, the present invention provides the following technical solutions: A high nickel positive electrode material and a preparation method thereof comprise the following steps: nickel sulfate, cobalt sulfate and manganese sulfate are prepared into metal salt solution according to the molar ratio of 83:11:5, wherein the total metal ion concentration is 2.0-2.2mol/L. An internal dopant, specifically chromium nitrate nonahydrate, was added to the metal salt solution, wherein the molar amount of chromium element was 1.5% of the total molar amount of nickel, cobalt and manganese. Under the protection of nitrogen, introducing a base solution into the reaction kettle, regulating the pH value of the base solution to 11.8 by ammonia water,