CN-121990617-A - Nickel cobalt lithium manganate positive electrode material and preparation method thereof

CN121990617ACN 121990617 ACN121990617 ACN 121990617ACN-121990617-A

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a nickel cobalt lithium manganate positive electrode material and a preparation method thereof. The invention solves the technical problems of poor cycle performance and low specific capacity of the existing nickel cobalt lithium manganate anode material. The preparation method comprises the steps of firstly adopting a coprecipitation process to synthesize precursor powder, then carrying out high-shear mixing on the precursor, lithium hydroxide, nano niobium oxide and magnesium fluoride, carrying out pre-oxidation and high-temperature oxygen-enriched gradient sintering on the mixed material, adopting a gradient reduction etching process in a cooling stage, carrying out surface shaping by matching with strong wind quenching, and finally carrying out jet milling and demagnetizing to obtain the nickel cobalt lithium manganate anode material. According to the invention, the radial ordered structure is constructed to effectively dissipate lattice respiratory stress, the multielement collaborative doping is utilized to stabilize the bulk phase structure, and the interfacial ion transmission dynamics is optimized through reduction-induced surface oxygen vacancies and lattice distortion layers, so that the collaborative strategy ensures the high stability of the material structure, and simultaneously greatly improves the deintercalation efficiency of active lithium.

Inventors

Fu Qingpan
GAO YUN
SHI JIANWEN

Assignees

扬州虹途电子材料有限公司
扬州虹瑞新能源有限公司

Dates

Publication Date: 20260508
Application Date: 20260209

Claims (7)

1. The preparation method of the nickel cobalt lithium manganate positive electrode material is characterized by comprising the following steps of: Dissolving nickel sulfate hexahydrate, cobalt sulfate heptahydrate and manganese sulfate monohydrate in deionized water according to a proportion, performing pulse pH control process, washing and drying to obtain precursor powder, performing step-by-step shearing and mixing on the precursor powder, lithium hydroxide, nano-niobium oxide and magnesium fluoride to obtain a mixed material, introducing ethanol after gradient sintering treatment of the mixed material, performing gradient reduction etching process, and performing jet milling and demagnetizing to obtain the nickel cobalt lithium manganate anode material.
2. The preparation method of the nickel cobalt lithium manganate positive electrode material is characterized by comprising the steps of weighing nickel sulfate hexahydrate, cobalt sulfate heptahydrate and manganese sulfate monohydrate according to a molar ratio, dissolving the nickel sulfate hexahydrate, the cobalt sulfate heptahydrate and the manganese sulfate monohydrate in deionized water to obtain a metal salt solution, adding the deionized water into a reaction kettle, adjusting pH value with ammonia water, heating to 50-60 ℃ under the protection of nitrogen gas, keeping stirring, then starting parallel flow feeding, adding the metal salt solution, a complexing agent and a precipitant, setting the flow rate of the metal salt solution to be 35-45mL/min, keeping the pH value of a system at 11.5 in the front stage of the reaction, switching a program to a pulse mode, stopping feeding after the reaction, performing filter pressing washing and vacuum drying to obtain the precursor powder, wherein the precipitant is sodium hydroxide solution, and the complexing agent is the ammonia water.
3. The preparation method of the nickel cobalt lithium manganate positive electrode material is characterized by comprising the steps of putting the precursor powder into a mixer, adding battery-grade lithium hydroxide micro powder, adding the nano niobium oxide and the magnesium fluoride, and stirring the mixture in a two-step method to obtain the mixed material.
4. The preparation method of the nickel cobalt lithium manganate positive electrode material is characterized by comprising the steps of sintering the mixed material, heating to 440-460 ℃, introducing oxygen-enriched air with the oxygen content of 40-50%, preserving heat, sintering, heating to 785-795 ℃ continuously, switching the atmosphere to high-purity oxygen, keeping the pressure of a hearth at micro positive pressure, and sintering at constant temperature for 11-13h to obtain the doped material.
5. The preparation method of the nickel cobalt lithium manganate positive electrode material is characterized in that when the temperature of a kiln is reduced to 650 ℃, oxygen supply is cut off, a vacuum pump system is started, the pressure of a hearth is pumped to vacuum, absolute ethyl alcohol steam is pumped through a bypass, carrier gas is nitrogen, the duration is 10-20min, after the treatment is completed, vacuumizing and ethanol injection are stopped, nitrogen is filled to normal pressure, and the material is cooled to obtain the nickel cobalt lithium manganate material.
6. The preparation method of the nickel cobalt lithium manganate positive electrode material is characterized in that the process of jet milling and demagnetizing comprises the steps of firstly coarsely milling the nickel cobalt lithium manganate material through a crusher, then grinding the nickel cobalt lithium manganate material in the jet mill, and removing magnetic foreign matters from the ground powder through an electromagnetic iron remover to obtain the nickel cobalt lithium manganate positive electrode material.
7. The nickel cobalt lithium manganate positive electrode material is characterized by comprising nickel sulfate hexahydrate, cobalt sulfate heptahydrate, manganese sulfate monohydrate, lithium hydroxide, nanometer niobium oxide, magnesium fluoride, sodium hydroxide and ammonia water as preparation raw materials, and is prepared by the preparation method of any one of claims 1-6.

Description

Nickel cobalt lithium manganate positive electrode material and preparation method thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a nickel cobalt lithium manganate positive electrode material and a preparation method thereof. Background With the continuous improvement of the long-life mileage requirement of new energy automobiles, layered nickel cobalt lithium manganate anode materials with high specific capacity and high energy density have become the mainstream choice of the market, and particularly, high-nickel systems and lithium-rich manganese-based systems are attracting attention because of the capability of providing reversible capacity exceeding 200 mAh/g. Conventional preparation processes typically involve preparing a precursor by co-precipitation, and mixing with a lithium source for high temperature solid phase sintering. In order to further improve the performance, coating (such as Al 2O3, LBO and the like) or bulk doping and other means are often adopted in the industry to attempt to construct a protective layer or a stable bulk structure on the surface of material particles. Despite the wide application of nickel cobalt lithium manganate materials, the practical application of the nickel cobalt lithium manganate materials still faces the double technical bottlenecks of poor cycle performance and difficult full play of specific capacity. On the one hand, in the deep lithium removal state, the material unit cells undergo severe nonlinear anisotropic shrinkage along the c-axis direction, so that huge mechanical stress is accumulated in the secondary particles to cause generation and expansion of inter-crystal microcracks, the microcracks damage the conductive network in the particles, fresh surfaces are continuously exposed and undergo side reactions with electrolyte, active substances are pulverized, the impedance is rapidly increased, and the cycle life is rapidly reduced. On the other hand, the high nickel material has high residual alkali on the surface and unstable thermodynamics, and is extremely easy to generate Li +/Ni2+ cation mixed discharge, which not only hinders a two-dimensional transmission channel of lithium ions, resulting in the reduction of the diffusion kinetics performance of the lithium ions, but also ensures that the specific discharge capacity of the material under the actual working condition is far lower than a theoretical value. Therefore, a nickel cobalt lithium manganate positive electrode material and a preparation method thereof are provided. Disclosure of Invention The invention aims to design a nickel cobalt lithium manganate positive electrode material and a preparation method thereof. The preparation method comprises the steps of firstly adopting a coprecipitation process to synthesize precursor powder, then carrying out high-shear mixing on the precursor, lithium hydroxide, nano niobium oxide and magnesium fluoride, carrying out pre-oxidation and high-temperature oxygen-enriched gradient sintering on the mixed material, adopting a gradient reduction etching process in a cooling stage, carrying out surface shaping by matching with strong wind quenching, and finally carrying out jet milling and demagnetizing to obtain the nickel cobalt lithium manganate anode material. According to the invention, the radial ordered structure is constructed to effectively dissipate lattice respiratory stress, the multielement collaborative doping is utilized to stabilize the bulk phase structure, and the interfacial ion transmission dynamics is optimized through reduction-induced surface oxygen vacancies and lattice distortion layers, so that the collaborative strategy ensures the high stability of the material structure, and simultaneously greatly improves the deintercalation efficiency of active lithium. In order to achieve the purpose, the invention provides the following technical scheme that the metal salts are all battery-level high-purity reagents. The invention provides a preparation method of a nickel cobalt lithium manganate positive electrode material, which comprises the following steps: Dissolving nickel sulfate hexahydrate, cobalt sulfate heptahydrate and manganese sulfate monohydrate in deionized water according to a proportion, performing pulse pH control process, washing and drying to obtain precursor powder, performing step-by-step shearing and mixing on the precursor powder, lithium hydroxide, nano-niobium oxide and magnesium fluoride to obtain a mixed material, introducing ethanol after gradient sintering treatment of the mixed material, performing gradient reduction etching process, and performing jet milling and demagnetizing to obtain the nickel cobalt lithium manganate anode material. Preferably, the precursor powder is prepared by weighing nickel sulfate hexahydrate, cobalt sulfate heptahydrate and manganese sulfate monohydrate according to the molar ratio of Ni to Co to Mn=8 to 1, dissolvi