Search

CN-122000325-A - Composite positive electrode material, preparation method thereof and battery

CN122000325ACN 122000325 ACN122000325 ACN 122000325ACN-122000325-A

Abstract

The application relates to a composite positive electrode material which is of a core-shell structure and comprises an inner core, and a first coating layer and a second coating layer which sequentially coat the inner core from inside to outside, wherein the first coating layer comprises barium selenide, and the second coating layer comprises carbon quantum dots. According to the application, through constructing double-layer cladding of the first cladding layer and the second cladding layer on the surface of the core, barium selenide and carbon quantum dots can cooperatively form a perfect and reliable conductive network, so that the overall electronic conductivity of the composite anode material can be remarkably improved, the charge transfer impedance is reduced, the migration of active ions is promoted, and the high rate performance and the cycle performance of the composite anode material can be further improved.

Inventors

  • WU LINGSHAN
  • CHAI DAJUN
  • LI ZHENG
  • GAO XINGYU
  • WANG SIXIAN
  • WANG YANG
  • GUO DEXIANG
  • YU HONGJIANG
  • YU ZHEXUN

Assignees

  • 江苏正力新能电池技术股份有限公司

Dates

Publication Date
20260508
Application Date
20260205

Claims (10)

  1. 1. The composite positive electrode material is characterized by being of a core-shell structure and comprising an inner core, and a first coating layer and a second coating layer which sequentially coat the inner core from inside to outside; The first cladding layer comprises barium selenide, and the second cladding layer comprises carbon quantum dots.
  2. 2. The composite positive electrode material according to claim 1, wherein the material of the inner core comprises lithium iron phosphate, a carbon coating layer is coated on the surface of the lithium iron phosphate, and/or the particle size of the inner core is 200 nm-1.5 μm.
  3. 3. The composite positive electrode material according to claim 1, wherein the thickness of the first coating layer is 1 nm-15 nm, and/or the thickness of the second coating layer is 1 nm-15 nm, and/or the mass ratio of the first coating layer to the second coating layer is (1:2) - (1:1).
  4. 4. The preparation method of the composite positive electrode material is characterized by comprising the following steps of: s1, mixing a material of a core, a barium source and a selenium source, adding a solvent, performing ball milling, and drying to obtain first mixed powder; S2, performing first heat treatment on the first mixed powder in a first inert gas atmosphere, and forming a first coating layer on the surface of the inner core, wherein the first coating layer comprises barium selenide; S3, adding the inner core with the surface coated with the first coating layer into the carbon quantum dot dispersion liquid, and performing dispersion treatment to obtain mixed slurry; and S4, carrying out second heat treatment on the second mixed powder in a second inert gas atmosphere, and forming a second coating layer on the surface of the first coating layer, wherein the second coating layer comprises carbon quantum dots, so as to obtain the composite anode material.
  5. 5. The method of producing a composite positive electrode material according to claim 4, wherein step S1 satisfies at least one of the following characteristics: (1) The material of the inner core comprises lithium iron phosphate, and a carbon coating layer is coated on the surface of the lithium iron phosphate; (2) The particle size of the inner core is 200 nm-1.5 mu m; (3) The barium source comprises barium acetate and/or barium carbonate; (4) The selenium source comprises selenium powder and/or phenylselenophene; (5) The solvent comprises absolute ethanol; (6) The rotation speed of the ball milling is 300-500 r/min, and the time is 4-6 h; (7) The temperature of the drying treatment is 80-100 ℃ and the time is 10-14 h.
  6. 6. The method for preparing a composite positive electrode material according to claim 4, wherein in the step S2, the temperature of the first heat treatment is 500-700 ℃, the heat preservation time is 3-5 h, and/or the thickness of the first coating layer is 1-15 nm.
  7. 7. The method for preparing the composite positive electrode material according to claim 4, wherein in the step S3, the dispersion treatment comprises stirring treatment and then ultrasonic treatment, and optionally, the stirring treatment time is 5-6 hours, and the ultrasonic treatment time is 30-60 minutes.
  8. 8. The method for preparing a composite positive electrode material according to claim 4, wherein in the step S4, the temperature of the second heat treatment is 350-400 ℃ and the heat preservation time is 2-4 hours, and/or the thickness of the second coating layer is 1-15 nm, and/or the mass ratio of the first coating layer to the second coating layer is (1:2) - (1:1).
  9. 9. The method for producing a composite positive electrode material according to any one of claims 4 to 8, wherein the step of producing the carbon quantum dot dispersion liquid comprises: heating a carbon source, and obtaining carbon quantum dot solids through melting and carbonization; dissolving the carbon quantum dot solid in deionized water, and uniformly mixing to obtain the carbon quantum dot dispersion liquid; the preparation step of the carbon quantum dot dispersion liquid satisfies at least one of the following characteristics: (1) The carbon source comprises at least one of citric acid, chitosan, vitamin C and amino acid; (2) The temperature of the heating treatment is 180-220 ℃; (3) The mixing treatment is ultrasonic treatment.
  10. 10. A battery comprising a positive electrode sheet, characterized in that the positive electrode sheet comprises the composite positive electrode material according to any one of claims 1 to 3 or comprises the composite positive electrode material produced by the production method of the composite positive electrode material according to any one of claims 4 to 9.

Description

Composite positive electrode material, preparation method thereof and battery Technical Field The invention relates to the technical field of batteries, in particular to a composite positive electrode material, a preparation method thereof and a battery. Background The lithium iron phosphate anode material has the advantages of high safety, long cycle life, environmental friendliness, low cost and the like, and is widely applied to the fields of power batteries and energy storage batteries at present. However, the cathode material itself has inherent defects of low intrinsic electron conductivity and slow diffusion rate of lithium ions, resulting in significant limitations in rate performance and cycle performance. In order to improve the conductivity and ion transport kinetics of lithium iron phosphate, modification means such as carbon coating, ion doping and particle nanocrystallization are generally adopted in the industry. The carbon coating is one of the technologies which are widely used, and the carbon layer is coated on the surface of the lithium iron phosphate particles, so that the electronic conductivity of the whole material can be improved, and the rate performance and the cycle performance of the lithium iron phosphate positive electrode material are improved. However, the carbon coating obtained by pyrolysis of the traditional carbon source (such as glucose, sucrose and the like) is usually amorphous carbon, the conductivity is limited, the coating is easy to generate uneven and discontinuous phenomena, and the construction of an electron conduction network is imperfect. Therefore, the improvement of the rate capability and the cycle performance of the lithium iron phosphate anode material is limited. Disclosure of Invention In view of the above, the embodiment of the application provides a composite positive electrode material, a preparation method thereof and a battery for solving at least one problem existing in the background art. In a first aspect, an embodiment of the present application provides a composite positive electrode material, where the composite positive electrode material is in a core-shell structure, and includes an inner core, and a first coating layer and a second coating layer that sequentially coat the inner core from inside to outside; The first cladding layer comprises barium selenide, and the second cladding layer comprises carbon quantum dots. In combination with the first aspect of the present application, in an alternative embodiment, the material of the inner core includes lithium iron phosphate, a carbon coating layer is coated on the surface of the lithium iron phosphate, and/or the particle size of the inner core is 200 nm-1.5 μm. With reference to the first aspect of the present application, in an optional embodiment, the thickness of the first coating layer is 1 nm-15 nm, and/or the thickness of the second coating layer is 1 nm-15 nm, and/or the mass ratio of the first coating layer to the second coating layer is (1:2) - (1:1). In a second aspect, an embodiment of the present application provides a method for preparing a composite positive electrode material, the method including the steps of: s1, mixing a material of a core, a barium source and a selenium source, adding a solvent, performing ball milling, and drying to obtain first mixed powder; S2, performing first heat treatment on the first mixed powder in a first inert gas atmosphere, and forming a first coating layer on the surface of the inner core, wherein the first coating layer comprises barium selenide; S3, adding the inner core with the surface coated with the first coating layer into the carbon quantum dot dispersion liquid, and performing dispersion treatment to obtain mixed slurry; and S4, carrying out second heat treatment on the second mixed powder in a second inert gas atmosphere, and forming a second coating layer on the surface of the first coating layer, wherein the second coating layer comprises carbon quantum dots, so as to obtain the composite anode material. With reference to the second aspect of the present application, in an alternative embodiment, step S1 satisfies at least one of the following features: (1) The material of the inner core comprises lithium iron phosphate, and a carbon coating layer is coated on the surface of the lithium iron phosphate; (2) The particle size of the inner core is 200 nm-1.5 mu m; (3) The barium source comprises barium acetate and/or barium carbonate; (4) The selenium source comprises selenium powder and/or phenylselenophene; (5) The solvent comprises absolute ethanol; (6) The rotation speed of the ball milling is 300-500 r/min, and the time is 4-6 h; (7) The temperature of the drying treatment is 80-100 ℃ and the time is 10-14 h. In an optional embodiment, in step S2, the temperature of the first heat treatment is 500 ℃ to 700 ℃ and the heat preservation time is 3h to 5h, and/or the thickness of the first coating layer is 1nm to 15nm. With referen