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CN-121983550-A - Positive electrode active material and lithium ion secondary battery

CN121983550ACN 121983550 ACN121983550 ACN 121983550ACN-121983550-A

Abstract

The application discloses a positive electrode active material and a lithium ion secondary battery. The positive electrode active material comprises a lithium-rich manganese-based material, a first coating layer and a second coating layer, wherein the first coating layer comprises a first fast ion conductor, the first coating layer coats part of the surface of the lithium-rich manganese-based material, the second coating layer comprises a first area and a second area which are connected with each other, the first area coats the lithium-rich manganese-based material which is not coated by the first coating layer, the first area comprises lithium halide or a compound formed by the lithium halide and the second fast ion conductor, the second area coats the first coating layer, and the second area comprises a compound formed by the lithium halide and the first fast ion conductor or a compound formed by the lithium halide and the first fast ion conductor and the second fast ion conductor. The two coating layers are tightly connected in space and function, so that rapid ion/electron continuous transmission, stable interface chemistry and durable physical protection are realized, and the high capacity exertion of the lithium-rich manganese-based material is ensured, and meanwhile, the rate performance and the cycling stability of the battery are improved.

Inventors

  • LI CHANGXIN
  • Zeng Jiajiang
  • Du Yunqiu
  • CHEN PING
  • Liu Zehuang

Assignees

  • 珠海冠启新材料有限公司

Dates

Publication Date
20260505
Application Date
20260209

Claims (10)

  1. 1. The positive electrode active material comprises a core and a coating layer, and is characterized in that the core comprises a lithium-rich manganese-based material, and the coating layer comprises a first coating layer and a second coating layer; the first coating layer comprises a first fast ion conductor and coats part of the surface of the lithium-rich manganese-based material; The second coating layer comprises a first region and a second region which are connected with each other, the first region coats the lithium-rich manganese-based material which is not coated by the first coating layer, the first region comprises lithium halide or a compound formed by the lithium halide and a second fast ion conductor, the second region coats the first coating layer, the second region comprises a compound formed by the lithium halide and the first fast ion conductor, or the second region comprises a compound formed by the lithium halide and the first fast ion conductor and the second fast ion conductor.
  2. 2. The positive electrode active material according to claim 1, wherein the coating ratio of the first coating layer is 1% to 50% based on the surface area of the lithium-rich manganese-based material; And/or, based on the mass of the second coating layer, the mass content of halogen element is 4% -65%, wherein the halogen element comprises at least one of Cl, br and F; and/or the thickness of the second coating layer is 10nm-150nm; and/or the thickness of the first coating layer is 10nm-50nm.
  3. 3. The positive electrode active material according to claim 1 or 2, wherein the lithium-rich manganese-based material has a chemical formula of Li 1+x Ni a Co b Mn c D d O e , D includes at least one of Al, ti, zr, ta, nb, mo, W, F, cl, br elements, x is 0.1≤x is 0.5, a is 0.1≤ 0.3,0.1≤b is 0.3, c is 0.5≤ 0.8,0.01≤d is 0.2,2≤e is 3; And/or, the first fast ion conductor and the second fast ion conductor each independently comprise at least one of Li 7 La 3 Zr 2-y E y O 12 、Li 1+z Al z Ti 2-z (PO 4 ) 3 、Li 3 PS 4 、Li 7 P 3 S 11 、Li 2 ZrO 3 、Li 4 Ti 5 O 12 , wherein E comprises at least one of Al, ga, ta, nb, and y is more than or equal to 0 and less than or equal to 0.6,0.05 and z is more than or equal to 0.2; And/or, the lithium halide comprises at least one of LiCl, liBr, liF.
  4. 4. The positive electrode active material according to claim 3, wherein the first cladding layer is Li 7 La 3 Zr 2- y E y O 12 , the first region in the second cladding layer is Li 4 PS 4 F, and the second region in the second cladding layer is Li 4 PS 4 F-Li 8 La 3 Zr 2-y E y O 12 F, wherein E includes at least one of Al, ga, ta, nb, and 0≤y≤0.6.
  5. 5. The positive electrode active material according to claim 1 or 2, wherein the lithium-rich manganese-based material includes Al, zr, and F elements, the mass content of Al element is 500 to 3000ppm, the mass content of Zr element is 500 to 3000ppm, and the mass content of F element is 1500 to 12000ppm based on the mass of the positive electrode active material; and/or the thickness of the first coating layer is 20nm-40nm; And/or the thickness of the second coating layer is 80nm-120nm.
  6. 6. The positive electrode active material according to claim 1, wherein characteristic peaks exist at 683eV-684eV and 685.5eV-687.5eV in XPS F1S spectrum of the positive electrode active material.
  7. 7. The positive electrode active material according to claim 1, wherein the positive electrode active material has a particle diameter Dv50 of 0.5 μm to 9 μm; and/or the particle size distribution SPAN value of the positive electrode active material is 0.5-2; and/or the positive electrode active material includes secondary particles agglomerated from primary particles having an average particle diameter of 0.2 μm to 1.0 μm.
  8. 8. The positive electrode active material according to claim 1, 2, 4, 6 or 7, wherein the positive electrode active material has a specific surface area of 1m 2 /g-4m 2 /g; and/or the positive electrode active material has an ionic conductivity of 10 -8 S/cm-10 -6 S/cm at 25 ℃.
  9. 9. A lithium ion secondary battery comprising a positive electrode sheet comprising a positive electrode current collector and a positive electrode active layer provided on at least one side surface in a thickness direction of the positive electrode current collector, characterized in that the positive electrode active layer comprises the positive electrode active material according to any one of claims 1 to 8.
  10. 10. The lithium ion secondary battery according to claim 9, wherein the lithium ion secondary battery comprises any one of an all-solid-state battery, a semi-solid-state battery, and a liquid battery.

Description

Positive electrode active material and lithium ion secondary battery Technical Field The application relates to the technical field of batteries, in particular to a positive electrode active material and a lithium ion secondary battery. Background Currently, continuous improvement of energy density of lithium ion secondary batteries as high-energy storage carriers is a core direction of industry development. Lithium-rich manganese-based (Li-RICH MANGANESE-based, LRM) materials are considered as one of the candidate active materials for next generation high energy density batteries because of their theoretical specific capacity exceeding 250 mAh/g. However, LRM materials still have a series of inherent defects in practical application, such as (1) unstable structure, in which LRM materials are easy to generate irreversible phase change in the charge and discharge process to cause continuous attenuation of capacity, (2) serious side reaction of interfaces, in which LRM materials are easy to generate oxygen escape under high voltage to oxidize electrolyte or solid electrolyte to generate unstable interface phase, further aggravate impedance increase and capacity attenuation, and (3) poor ion/electron conductivity, in which intrinsic ion and electron conductivity of LRM materials are poor, passivation layers are easy to form on surfaces to cause remarkable increase of interface impedance. Disclosure of Invention In view of the above, the technical problems to be solved by the application are to overcome the problems of unstable structure, serious side reaction of the interface and poor ion/electron conductivity of the existing lithium-rich manganese-based material, and further to provide a lithium-rich manganese-based material with good structural stability, high interface compatibility with electrolyte and quick ion conduction, a preparation method thereof and a lithium ion secondary battery comprising the lithium-rich manganese-based material. In order to achieve the above purpose, the present application adopts the following technical scheme. According to a first aspect of the embodiment of the application, a positive electrode active material is provided, and the positive electrode active material comprises a core and a coating layer, wherein the core comprises a lithium-rich manganese-based material, the coating layer comprises a first coating layer and a second coating layer, the first coating layer comprises a first fast ion conductor, the first coating layer coats part of the surface of the lithium-rich manganese-based material, the second coating layer comprises a first area and a second area which are connected with each other, the first area coats the lithium-rich manganese-based material which is not coated by the first coating layer, the first area comprises lithium halide or a compound formed by the lithium halide and the second fast ion conductor, the second area coats the first coating layer, and the second area comprises a compound formed by the lithium halide and the first fast ion conductor or a compound formed by the lithium halide and the first fast ion conductor and the second fast ion conductor. In some alternative embodiments, the halogen element comprises at least one of Cl, br, and F in an amount of 4% to 65% by mass based on the mass of the second coating layer. In some alternative embodiments, the second cladding layer has a thickness of 10nm to 150nm. Further, in some alternative embodiments, the second cladding layer has a thickness of 80nm to 120nm. In some alternative embodiments, the first cladding layer has a thickness of 10nm to 50nm. Further, in some alternative embodiments, the first cladding layer has a thickness of 20nm to 40nm. In some alternative embodiments, the lithium-rich manganese-based material has a chemical formula of Li 1+xNiaCobMncDdOe, D includes at least one of Al, ti, zr, ta, nb, mo, W, F, cl, br elements, 0.1≤x≤0.5, 0.1≤a≤ 0.3,0.1≤b≤0.3, 0.5≤c≤ 0.8,0.01≤d≤ 0.2,2≤e≤3. Further, in some alternative embodiments, the lithium-rich manganese-based material includes Al, zr, and F elements, and the mass content of Al element is 500 to 3000ppm, the mass content of Zr element is 500 to 3000ppm, and the mass content of F element is 1500 to 12000ppm, based on the mass of the positive electrode active material. In some alternative embodiments, the first fast ion conductor and the second fast ion conductor each independently comprise at least one of Li7La3Zr2-yEyO12、Li1+zAlzTi2-z(PO4)3、Li3PS4、Li7P3S11、Li2ZrO3、Li4Ti5O12, wherein E comprises at least one of Al, ga, ta, nb, 0≤y≤ 0.6,0.05≤z≤0.2. In some alternative embodiments, the lithium halide includes at least one of LiCl, liBr, liF. Further, in some alternative embodiments, the first cladding layer is Li 7La3Zr2-yEyO12, the first region in the second cladding layer is Li 4PS4 F, and the second region in the second cladding layer is Li 4PS4F-Li8La3Zr2-yEyO12 F, wherein E comprises at least one of Al, ga, ta, nb and 0≤y≤0.