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CN-121192139-B - High-voltage lithium cobalt oxide positive electrode material and preparation method thereof

CN121192139BCN 121192139 BCN121192139 BCN 121192139BCN-121192139-B

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a high-voltage lithium cobaltate positive electrode material and a preparation method thereof. The technical proposal comprises the following chemical composition of the anode material Among them, Is at least two elements selected from Al, mg, ti, zr, , , . The invention realizes breakthrough promotion of the performance of the high-voltage lithium cobalt oxide anode material through triple strategies of multi-element collaborative doping, core-shell structure design and surface defect regulation, and particularly through the synergistic effect of specific element combination Al+Mg+Ti and the coupling effect of F element distributed in a gradient manner and a nano defect structure, the structural phase change and interface side reaction in the high-voltage circulation process are effectively inhibited, and the cycle life and the thermal stability of the material are obviously improved.

Inventors

  • HUANG JIAN
  • WEI DONGHAI
  • GUO DAOCHUAN
  • LI SHUO

Assignees

  • 东莞市金赛尔电池科技有限公司

Dates

Publication Date
20260512
Application Date
20250918

Claims (10)

  1. 1. A high-voltage lithium cobalt oxide positive electrode material is characterized in that the chemical composition of the positive electrode material is that Wherein Is at least two elements selected from Al, mg, ti, zr, , , ; The positive electrode material has a core-shell structure, the inner core is a lithium cobalt oxide phase rich in lithium, and the outer shell is a material containing A composite oxide layer of an element; In the outer casing The content of the elements gradually increases from inside to outside, and The concentration of the element in the shell gradually decreases from inside to outside, and the element is in the shell The element content is increased by 1.5-3 times from the inner layer to the outer layer, The element content is reduced by 30% -60% from the inner layer to the outer layer; the primary particle surface of the positive electrode material has a nano-scale oxygen vacancy defect structure, and the oxygen vacancy defect structure is distributed with uniform dispersion And the depth of the oxygen vacancy defect is 5-50nm.
  2. 2. The high-voltage lithium cobaltate cathode material according to claim 1, wherein the The elements are a combination of Al and Mg, wherein the mole content of Al is The molar content of Mg is And (2) and 。
  3. 3. The high-voltage lithium cobaltate cathode material according to claim 1, wherein the The elements are a combination of Al, mg and Ti, wherein the mole content of Al is The molar content of Mg is The molar content of Ti is And (2) and 。
  4. 4. The high-voltage lithium cobaltate positive electrode material according to claim 1, wherein in the core-shell structure, an inner core accounts for 70% -90% of the whole particle volume, and the thickness of an outer shell is 50-200nm.
  5. 5. The high-voltage lithium cobaltate positive electrode material according to claim 1, wherein the specific surface area of the positive electrode material is 0.2-0.8m 2 /g, and the tap density is 2.8-3.4g/cm 3 .
  6. 6. A method for preparing the high-voltage lithium cobaltate positive electrode material according to any one of claims 1 to 5, comprising the steps of: Preparing a precursor, namely cobalt salt, Preparing the salt of the element into a mixed solution according to the stoichiometric ratio, adding a precipitator for coprecipitation reaction to obtain the product containing the element A cobalt hydroxide precursor of an element; The lithiation treatment, namely mixing the precursor with a lithium source, and performing first high-temperature sintering in an oxygen atmosphere to obtain a lithiation product; mixing the lithiation product with a fluorine source, and performing secondary high-temperature sintering in an inert atmosphere, wherein the temperature of the secondary high-temperature sintering is lower than that of the primary high-temperature sintering; The defect structure is regulated, namely the product subjected to surface fluorination treatment is subjected to low-temperature annealing treatment in an oxygen-containing atmosphere to form the nanoscale defect structure, the low-temperature annealing treatment is performed in the oxygen-containing atmosphere, surface lattice oxygen is induced to be removed to form the oxygen vacancy defect, and meanwhile, the oxygen vacancy defect is promoted to be formed The elements migrate to the oxygen vacancies and disperse uniformly.
  7. 7. The method for preparing the high-pressure lithium cobalt oxide positive electrode material according to claim 6, wherein the temperature of the first high-temperature sintering is 850-950 ℃, the heat preservation time is 8-15 hours, the temperature of the second high-temperature sintering is 600-750 ℃, the heat preservation time is 4-8 hours, the temperature of the low-temperature annealing treatment is 300-500 ℃, and the heat preservation time is 2-6 hours.
  8. 8. The method for preparing a high-voltage lithium cobaltate positive electrode material according to claim 6, wherein the fluorine source is 、 、 At least one of the fluorine sources, and the addition amount of the fluorine source is 0.5% -3% of the mass of the lithiated product.
  9. 9. The method for preparing a high-voltage lithium cobaltate positive electrode material according to claim 6, wherein the lithium source is at least one of lithium carbonate and lithium hydroxide, and the molar ratio of the lithium source to the metal element in the precursor is 1.01:1 to 1.05:1.
  10. 10. The method for preparing high-pressure lithium cobaltate cathode material according to claim 6, wherein the precipitant is a mixed solution of sodium hydroxide and ammonia water, the pH value of the coprecipitation reaction is controlled to be 10.5-12.0, and the reaction temperature is controlled to be 40-60 ℃.

Description

High-voltage lithium cobalt oxide positive electrode material and preparation method thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a high-voltage lithium cobaltate positive electrode material and a preparation method thereof. Background The ion battery is widely applied to the fields of portable electronic equipment, electric automobiles, energy storage systems and the like due to the advantages of high energy density, long cycle life, no memory effect and the like. Lithium cobaltate (LiCoO 2) is used as the earliest commercialized lithium ion battery anode material, and is still the main stream anode material in the consumer electronics field by virtue of the characteristics of stable structure, flat charge and discharge platform, mature preparation process and the like. However, the practical specific capacity of the traditional lithium cobaltate material is only 140-160mAh/g, which is far lower than the theoretical specific capacity (274 mAh/g), and the requirements of a new generation of high-energy-density batteries are difficult to meet. Increasing the charge cutoff voltage of lithium cobaltate materials (e.g., from 4.2V to above 4.5V) is an effective way to increase their specific capacity. When the charging voltage is higher than 4.35V,The stripping amount is increased, and the specific capacity of the material can exceed 200mAh/g. However, lithium cobaltate materials face the following prominent problems under high pressure conditions: The structural stability is reduced, and in the deep lithium removal state, The content is increased, lattice oxygen precipitation is easy to be caused, so that the material is converted from a layered structure to spinel or rock salt phase, and irreversible capacity loss is caused; The interface side reaction is aggravated by the fact that electrolyte is subjected to oxidative decomposition on the surface of the positive electrode material under high voltage, acidic substances such as generated HF and the like can corrode the positive electrode material, dissolve Co element and migrate to the negative electrode, so that the internal resistance of the battery is increased and the cycle performance is worsened; And the thermal stability is poor, namely the lithium cobaltate material in a high-pressure state is easy to generate severe exothermic reaction in a high-temperature environment, so that the thermal runaway of the battery is caused, and potential safety hazards exist. In order to solve the problems, the prior art mainly adopts the following means: Element doping, namely, improving the structural stability or interface stability of the material by introducing metal elements such as Al, mg, ti and the like or nonmetal elements such as F, P and the like; Coating a protective layer such as oxide (such as Al 2O3、ZrO2), fluoride (such as LiF) or phosphate (such as AlPO 4) on the surface of the material to inhibit electrolyte erosion; Morphology regulation, namely optimizing a lithium ion diffusion path by controlling the particle morphology, particle size distribution or specific surface area of the material. However, the prior art still has the defects that the effect of doping a single element is limited, the excessive doping can reduce the electron/ion conductivity of the material, the surface coating layer can increase the interface impedance, the multiplying power performance of the battery is influenced, the material structure degradation and the interface side reaction are mutually promoted under high pressure, and the long-term stability is difficult to realize by a single modification means. Therefore, the development of a technical scheme capable of simultaneously solving the problems of structural stability, interface compatibility and thermal stability of the high-voltage lithium cobaltate material has important practical significance. Disclosure of Invention The invention aims at solving the problems of poor structural stability, interface compatibility and thermal stability of the existing high-pressure lithium cobalt oxide material in the background art, and provides a high-pressure lithium cobalt oxide positive electrode material and a preparation method thereof. In a first aspect, the present application provides a high-voltage lithium cobalt oxide positive electrode material having a chemical composition of, wherein,Is at least two elements selected from Al, mg, ti, zr,,,; The positive electrode material has a core-shell structure, the inner core is a lithium cobalt oxide phase rich in lithium, and the outer shell is a material containingA composite oxide layer of an element; In the outer casing The content of the elements gradually increases from inside to outside, andThe concentration of the element in the shell gradually decreases from inside to outside, and the element is in the shellThe element content is increased by 1.5-3 times from the inner layer to the outer layer,The eleme