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CN-122025563-A - Positive electrode material, preparation method thereof, positive electrode plate and secondary battery

CN122025563ACN 122025563 ACN122025563 ACN 122025563ACN-122025563-A

Abstract

A positive electrode material, a preparation method thereof, a positive electrode plate and a secondary battery. The positive electrode material comprises a base material and a coating layer, wherein the coating layer is at least coated on a part area of the base material, the coating layer comprises Li element and N element, the N element is at least one selected from tungsten, molybdenum, antimony and zirconium, the mass ratio of the Li element after XPS etching for 0 seconds and 4 seconds from the surface of the positive electrode material is Z Li‑XPS(0 Second of ) and Z Li‑XPS(4 Second of ) respectively, wherein Z Li‑XPS(4 Second of ) is 10% -70%, and Z Li‑XPS(0 Second of ) ＜Z Li‑XPS(4 Second of ) . The surface layer low Li component inner layer high Li component of the positive electrode material is beneficial to forming compressive stress on the surface of the material, improving the Li + deintercalation rate, prolonging the cycle life, simultaneously inhibiting the volume strain in the charging and discharging process of active substances and improving the safety.

Inventors

  • WANG HAOYI
  • ZHANG WEI
  • SONG XIONG
  • WU XIAOZHEN
  • YANG SHUNYI
  • HUANG YOUYUAN
  • ZHANG JINLONG

Assignees

  • 贝特瑞（江苏）新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20241101

Claims (10)

  1. 1. The positive electrode material is characterized by comprising a matrix material and a coating layer, wherein the coating layer is coated on at least a partial area of the matrix material, the coating layer comprises Li element and N element, and the N element is at least one of tungsten, molybdenum, antimony and zirconium; And etching the surface of the positive electrode material by using an X-ray photoelectron spectrometer (XPS) for 0 second and 4 seconds, wherein the mass ratio of the Li element is Z Li-XPS(0 Second of ) and Z Li-XPS(4 Second of ) respectively, and Z Li-XPS(4 Second of ) is 10% -70% and Z Li-XPS(0 Second of ) ＜Z Li-XPS(4 Second of ) .
  2. 2. The positive electrode material according to claim 1, wherein a mass ratio Z Li-XPS(4 Second of ) of the Li element at 4 seconds and a mass ratio Z Li-XPS(0 Second of ) of the Li element at 0 seconds are subtracted from a surface of the positive electrode material by XPS etching, and the mass ratio Z Li-XPS(8 Second of ) of the Li element at 8 seconds and the mass ratio Z Li-XPS(4 Second of ) of the Li element at 4 seconds are expressed as Z Li-XPS(4 Second of ) -Z Li-XPS(0 Second of ) >Z Li-XPS(8 Second of ) -Z Li-XPS(4 Second of ) .
  3. 3. The positive electrode material according to claim 1, wherein the mass ratio of Li element at 0 seconds is 10 to 60% by XPS etching from the surface of the positive electrode material, the mass ratio of Li element at 4 seconds is 10 to 70% by XPS etching, and the mass ratio of Li element at 8 seconds is 10 to 75% by XPS etching.
  4. 4. The positive electrode material of claim 1, wherein the coating layer has a chemical formula of Li d N e O f , wherein 0< d <0.5,0< e <0.002,0< f≤2.
  5. 5. The positive electrode material according to claim 4, wherein the mass ratio of the N element in the positive electrode material is 500ppm to 2000ppm.
  6. 6. The positive electrode material according to claim 1, wherein the positive electrode material has a chemical formula of Li b Ni x Co y F z N h M m O 2 , wherein b≤ 1.05,0.8≤x≤1, 0≤y+z≤0.2, x+y+z+h+m= 1,0.0001≤h≤ 0.003,0≤m <1, and the element F is at least one selected from Mn and Al, and the element M is at least one selected from Ca, ti, zr, sr, mg, sb, Y, la.
  7. 7. The positive electrode material of claim 1, wherein the positive electrode material meets at least one of the following characteristics: (1) The thickness of the coating layer is 1-5 nm; (2) The matrix material comprises secondary particles, wherein the secondary particles comprise a plurality of primary particles, and the secondary particles are spherical or spheroid; (3) The specific surface area of the positive electrode material is 0.5m 2 /g～2.0m 2 /g; (4) The bulk density of the positive electrode material is 1.0g/m 3 ～3.0g/m 3 ; (5) The powder conductivity of the positive electrode material under the pressure of 4kN/cm 2 is more than 0.02S/cm.
  8. 8. A method for producing the positive electrode material according to any one of claims 1 to 7, comprising: Mixing an oxide or hydroxide precursor of the positive electrode material with a lithium source, and sintering the mixture to obtain a primary sintering product; crushing and dispersing the primary sintering product, and carrying out lithium-supplementing re-sintering on the dispersed primary sintering product to obtain a re-sintered product; washing the re-sintered product with water, press-filtering the washed re-sintered product to obtain a filter cake, and Spraying a suspension containing a coating material on the surface of the filter cake, and continuously stirring and reacting to enable the coating element in the coating material to react with lithium in the re-sintered product to form a coating layer, thereby obtaining the anode material.
  9. 9. A positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, characterized in that the positive electrode active material layer comprises the positive electrode material according to any one of claims 1 to 7.
  10. 10. A secondary battery comprising a case, an electrode assembly, and an electrolyte or electrolyte, both of which are located in the case, the electrode assembly comprising a separator and a negative electrode tab, characterized in that the electrode assembly further comprises the positive electrode tab according to claim 9, the separator being disposed between the positive electrode tab and the negative electrode tab.

Description

Positive electrode material, preparation method thereof, positive electrode plate and secondary battery Technical Field The application relates to the technical field of battery positive electrode materials, in particular to a positive electrode material, a preparation method thereof, a positive electrode plate and a secondary battery. Background At present, the lithium ion battery is widely applied to the field of new energy automobiles, however, the energy density is not high enough, the single-charging endurance mileage is short, and the requirements of wide automobile consumers cannot be met. Therefore, there is an urgent need to further increase the energy density of the lithium ion battery, and the development of a positive electrode material having a higher specific capacity is a key to increasing the energy density of the lithium ion battery. Increasing the Ni content of the positive electrode material can increase the specific discharge capacity and energy density of the positive electrode material. However, the existing high-nickel positive electrode material has lower structural stability and stronger volume strain in the charge and discharge process, so that the safety of a battery is seriously threatened, and the wide application of the high-nickel positive electrode material is limited. Disclosure of Invention In view of this, in order to solve at least one of the above drawbacks, the present application provides a positive electrode material. In addition, the application also provides a preparation method of the positive electrode material, a positive electrode plate using the positive electrode material and a secondary battery. In a first aspect, an embodiment of the present application provides a positive electrode material, where the positive electrode material includes a base material and a coating layer, the coating layer is at least coated on a partial area of the base material, the coating layer includes a Li element and an N element, the N element is at least one element selected from tungsten, molybdenum, antimony and zirconium, and mass ratios of the Li element after etching from a surface of the positive electrode material by using XPS for 0 second and 4 seconds are Z Li-XPS(0 Second of ) and Z Li-XPS(4 Second of ), respectively, where Z Li-XPS(4 Second of ) is 10% -70% and Z Li-XPS(0 Second of )＜ZLi-XPS(4 Second of ). In some possible embodiments, the mass ratio Z Li-XPS(4 Second of ) of the Li element at 4 seconds and the mass ratio Z Li-XPS(0 Second of ) of the Li element at 0 seconds are etched from the surface of the positive electrode material by XPS, and the mass ratio Z Li-XPS(8 Second of ) of the Li element at 8 seconds and the mass ratio Z Li-XPS(4 Second of ) of the Li element at 4 seconds are subtracted from each other, which is denoted as Z Li-XPS(4 Second of )-ZLi-XPS(0 Second of )>ZLi-XPS(8 Second of )-ZLi-XPS(4 Second of ). In some possible embodiments, the mass ratio of the Li element at 0 second is 10% -60% by XPS etching from the surface of the positive electrode material, the mass ratio of the Li element at 4 seconds is 10% -70% by XPS etching, and the mass ratio of the Li element at 8 seconds is 10% -75% by XPS etching. In some possible embodiments, the cladding layer has a chemical formula of Li dNeOf, where 0< d <0.5,0< e <0.002,0< f≤2. In some possible embodiments, the mass ratio of the N element in the positive electrode material is 500ppm to 2000ppm. In some possible embodiments, the positive electrode material has a chemical formula of Li bNixCoyFzNhMmO2, wherein 0.95≤b≤ 1.05,0.8≤x <1,0< y+z≤0.2, x+y+z+h+m= 1,0.0001≤h≤ 0.003,0≤m <1, the element F being selected from at least one of Mn and Al, the element M being selected from at least one of Ca, ti, zr, sr, mg, sb, Y, la. In some possible embodiments, the thickness of the coating layer is 1-5 nm. In some possible embodiments, the matrix material comprises secondary particles comprising a plurality of primary particles, the secondary particles being spherical or spheroid-like. In some possible embodiments, the specific surface area of the positive electrode material is 0.5m 2/g～2.0m2/g. In some possible embodiments, the bulk density of the positive electrode material is 1.0g/m 3～3.0g/m3. In some possible embodiments, the positive electrode material has a powder conductivity greater than 0.02S/cm at 4kN/cm 2 under pressure. The embodiment of the application also provides a preparation method of the positive electrode material, which comprises the steps of mixing an oxide or hydroxide precursor of the positive electrode material with a lithium source, sintering the mixture to obtain a primary sintered product, crushing and dispersing the primary sintered product, supplementing lithium to the dispersed primary sintered product, re-sintering to obtain a re-sintered product, washing the re-sintered product with water, and carrying out pressure filtration on the re-sintered product after washing to obtain a filt