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CN-121983554-A - Positive electrode active material, preparation method and application thereof

CN121983554ACN 121983554 ACN121983554 ACN 121983554ACN-121983554-A

Abstract

The application discloses a positive electrode active material, a preparation method and application thereof. The positive electrode active material comprises a ternary material, wherein the ternary material comprises a nickel cobalt lithium manganate core and a first coating layer coated on the nickel cobalt lithium manganate core, the chemical formula of the first coating layer is Li (Al x Co 1‑x )O 2‑δ F δ , wherein x is more than or equal to 0.1 and less than or equal to 0.6,0.05 and delta is more than or equal to 0.2. The positive electrode active material can improve interface stability, and when the ternary material is compounded with a lithium iron phosphate material, interface compatibility of the ternary material and the lithium iron phosphate material can be improved.

Inventors

  • ZHANG HUIYING
  • Niu Yingge
  • YU HONGJIANG
  • YU ZHEXUN
  • SUN RUILONG

Assignees

  • 江苏正力新能电池技术股份有限公司

Dates

Publication Date
20260505
Application Date
20260226

Claims (10)

  1. 1. The positive electrode active material is characterized by comprising a ternary material, wherein the ternary material comprises a nickel cobalt lithium manganate core and a first coating layer coated on the nickel cobalt lithium manganate core, and the chemical formula of the first coating layer is Li (Al x Co 1-x )O 2-δ F δ, , wherein x is more than or equal to 0.1 and less than or equal to 0.6,0.05 and delta is more than or equal to 0.2).
  2. 2. The positive electrode active material according to claim 1, further comprising a fast ion conductor layer coated on the surface of the first coating layer.
  3. 3. The positive electrode active material according to claim 2, wherein at least one of the following conditions is satisfied: (1) The material of the fast ion conductor layer is Li 1 . 3 Al 0 . 3 Ti 1 . 7 (PO 4 ) 3 ; (2) The thickness of the first coating layer is 10-20 nm; (3) The thickness of the fast ion conductor layer is 5-15nm.
  4. 4. The positive electrode active material of claim 1, further comprising a lithium iron phosphate material comprising a lithium iron phosphate core and a conductive layer coated on the lithium iron phosphate core, wherein the conductive layer has an electron conductivity of greater than 1S/cm.
  5. 5. The positive electrode active material according to claim 4, wherein: The material of the conductive layer is carbon material or poly 3, 4-ethylenedioxythiophene-polystyrene sulfonate, and/or, The thickness of the conductive layer is 2-5 nm.
  6. 6. The positive electrode plate is characterized by comprising: positive electrode current collector substrate, and The positive electrode material is arranged on the surface of the positive electrode current collector matrix; The positive electrode material comprising a conductive agent, a binder, and the positive electrode active material according to claim 4 or 5; The binder is polyvinylidene fluoride-hexafluoropropylene copolymer, and the main chain is grafted with phosphorus-containing functional group-PO 3 H 2 ; The weight ratio of the positive electrode active material to the conductive agent to the binder is positive electrode active material to the conductive agent to the binder=93-97:2-5:1-2.
  7. 7. A method of making a positive electrode sheet according to claim 6, comprising the steps of: s1, preparation of a ternary material: S1a, mixing a mixed solution containing an aluminum source, a cobalt source, a fluorine source and a lithium source with NCM particles, and evaporating to obtain a precursor, and performing first calcination treatment on the precursor to form a ternary material with the surface coated with Li (Al x Co 1-x )O 2-δ F δ , wherein the molar dosages of the aluminum source, the cobalt source, the fluorine source and the lithium source meet the conditions that Al3 + ：Co² + ：F - ：Li + =0.01-0.025:0.01-0.025:0.004-0.05:0.002-0.005; S1b, mixing the ternary material obtained in the step S1a with Li 1 . 3 Al 0 . 3 Ti 1 . 7 (PO 4 ) 3 sol, centrifuging to obtain a ternary material coated with Li 1 . 3 Al 0 . 3 Ti 1 . 7 (PO 4 ) 3 gel, and drying and calcining the ternary material coated with Li 1 . 3 Al 0 . 3 Ti 1 . 7 (PO 4 ) 3 gel for the second time to obtain a ternary material coated with double layers; S2, preparing a lithium iron phosphate material, namely mixing a carbon source with LFP particles, drying, and calcining for the third time to obtain the lithium iron phosphate material with the surface coated with the carbon conductive layer; S3, preparing a positive electrode plate, namely mixing the ternary material obtained in the step S1b, the lithium iron phosphate material obtained in the step S2, a conductive agent and a binder in a solvent to obtain positive electrode slurry; And coating the positive electrode slurry on a positive electrode current collector substrate, and drying and tabletting to obtain the positive electrode plate.
  8. 8. The method according to claim 7, wherein in the step S1a, the first calcination treatment is a two-stage calcination treatment performed under an oxygen atmosphere, wherein the first calcination treatment is performed by heating to 250-450 ℃ at 2-5 ℃ per minute and maintaining the temperature for 1-4 hours, and the second calcination treatment is performed by heating to 600-800 ℃ at 2-5 ℃ per minute and maintaining the temperature for 6-12 hours; The aluminum source is at least one of aluminum nitrate, aluminum chloride and aluminum sulfate; The cobalt source is at least one of cobalt acetate, cobalt chloride and cobalt nitrate; The fluorine source is at least one of ammonium fluoride, sodium fluoride and potassium fluoride; The lithium source is at least one of lithium hydroxide, lithium nitrate, lithium carbonate, lithium dihydrogen phosphate and lithium chloride; in the step S1b, the second calcination treatment is specifically performed by heating to 550-800 ℃ at 2-5 ℃ per min under the protection of argon atmosphere, and preserving heat for 2-8 hours.
  9. 9. The method of claim 7, wherein in the step S2, the third calcination is performed by heating to 400-850 ℃ at 2-5 ℃ per min under a weak reducing atmosphere, and preserving heat for 4-8 hours; In the step S3, the mass ratio of the ternary material to the lithium iron phosphate material is 8:2-2:8.
  10. 10. A lithium ion battery comprising the positive electrode sheet according to claim 6 and/or the positive electrode sheet produced by the production method according to any one of claims 7 to 9.

Description

Positive electrode active material, preparation method and application thereof Technical Field The application relates to the technical field of lithium ion batteries, in particular to a positive electrode active material, a preparation method and application thereof. Background Along with the continuous increase of the global demand for clean energy and sustainable development, the lithium ion battery has been widely applied in various fields such as mobile electronic equipment, electric automobiles and large-scale energy storage by virtue of the characteristics of high energy density, stable circulation and the like. The positive electrode material is used as one of key components of the lithium ion battery, and the performance of the positive electrode material directly influences the overall performance of the battery. Therefore, the method has important practical significance for researching the lithium battery anode material. The lithium ion battery positive electrode material needs to have both high energy density and high safety. Compared with lithium iron phosphate (LFP), ternary materials (NCM) have a high specific capacity, but suffer from the disadvantages of poor ionic conductivity and high interface impedance. In addition, the ternary material (NCM) with high specific capacity and the lithium iron phosphate (LFP) with high stability are composited for use, so that the performance complementation can be realized theoretically, however, the problem of poor interface compatibility in practical application can occur, and the problems include mismatching of electrochemical windows, increase of interface impedance, difference of ion/electron transmission characteristics and the like. Disclosure of Invention The invention aims to provide a positive electrode active material, a preparation method and application thereof. The positive electrode active material can improve the ionic conductivity of the ternary material, reduce the interface impedance of the ternary material and improve the interface stability, and especially can improve the interface compatibility of the ternary material and the lithium iron phosphate material when the ternary material and the lithium iron phosphate material are used in a composite mode. For the purpose of the invention, the following technical scheme is adopted: in one aspect, the invention provides a positive electrode active material, which comprises a ternary material, wherein the ternary material comprises a nickel cobalt lithium manganate core and a first coating layer coated on the nickel cobalt lithium manganate core, and the chemical formula of the first coating layer is Li (Al xCo1-x)O2-δFδ, wherein x is more than or equal to 0.1 and less than or equal to 0.6,0.05 and delta is more than or equal to 0.2. In an embodiment of the present invention, the positive electrode active material further includes a fast ion conductor layer coated on the surface of the first coating layer. Preferably, the material of the fast ion conductor layer is Li 1.3Al0.3Ti1.7(PO4)3 (LATP). Preferably, the thickness of the first coating layer is 10-20 nm a. Preferably, the thickness of the fast ion conductor layer is 5-15nm. In an embodiment of the present invention, the positive electrode active material further includes a lithium iron phosphate material including a lithium iron phosphate core and a conductive layer coated on the lithium iron phosphate core, the conductive layer having an electron conductivity of greater than 1S/cm. In an embodiment of the present invention, the material of the conductive layer is a carbon material or poly 3, 4-ethylenedioxythiophene-polystyrene sulfonate. Preferably, the thickness of the conductive layer is 2-5 nm a. In an embodiment of the present invention, the surface of the conductive layer is further coated with a lithium iron phosphate buffer layer. Preferably, the thickness of the lithium iron phosphate buffer layer is 1-3nm. In another aspect, the present invention also provides a positive electrode sheet, including: positive electrode current collector substrate, and The positive electrode material is arranged on the surface of the positive electrode current collector matrix; The positive electrode material comprises a conductive agent, a binder and the positive electrode active material; The binder is polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) and the backbone is grafted with a phosphorus-containing functional group-PO 3H2 (i.e., phosphonic acid group-PO (OH) 2). Preferably, the weight ratio of the positive electrode active material to the conductive agent to the binder is positive electrode active material to the conductive agent=93-97:2-5:1-2. In still another aspect, the present invention also provides a method for preparing the positive electrode sheet as described above, which includes the following steps: s1, preparation of a ternary material: S1a, mixing a mixed solution containing an aluminum source, a cobalt s