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CN-122025564-A - Positive electrode material, preparation method thereof, positive electrode plate and secondary battery

CN122025564ACN 122025564 ACN122025564 ACN 122025564ACN-122025564-A

Abstract

A positive electrode material, a preparation method thereof, a positive electrode plate and a secondary battery. The positive electrode material comprises a substrate and a coating layer coated on the surface of the substrate, wherein the coating layer comprises Li and W, the analysis is carried out in the depth direction of particles of the positive electrode material by XPS, and the sum of atomic weight ratios of Li+W measured after 0 seconds, 4 seconds and 8 seconds of XPS etching is above 80%. The surface of the positive electrode material provided by the application is provided with a complete and uniform coating layer, which is beneficial to improving the cycle life and the thermal stability of the positive electrode material.

Inventors

  • WANG HAOYI
  • CHEN XIAOQING
  • LIANG WENJIE
  • SONG XIONG
  • WU XIAOZHEN
  • YANG SHUNYI
  • HUANG YOUYUAN

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. A positive electrode material is characterized by comprising a matrix and a coating layer, wherein the coating layer is coated on the surface of the matrix, the coating layer comprises Li element and W element, the positive electrode material meets the conditions that Z (Li+W)-XPS(0 Second of ) 、Z (Li+W)-XPS(4 Second of ) and Z (Li+W)-XPS(8 Second of ) are both more than 80 percent, and the positive electrode material comprises a coating layer, The method comprises the steps of analyzing the depth direction of particles of the positive electrode material by an X-ray photoelectron spectrometer (XPS), wherein the sum of atomic weight ratios of Li atoms and W atoms measured after etching the surface of the positive electrode material for 0 seconds by XPS is Z (Li+W)-XPS(0 Second of ) , the sum of atomic weight ratios of Li atoms and W atoms measured after etching the surface of the positive electrode material for 4 seconds by XPS is Z (Li+W)-XPS(4 Second of ) , and the sum of atomic weight ratios of Li atoms and W atoms measured after etching the surface of the positive electrode material for 8 seconds by XPS is Z (Li+W)-XPS(8 Second of ) .
  2. 2. The positive electrode material according to claim 1, wherein the relation between Z (Li+W)-XPS(0 Second of ) 、Z (Li+W)-XPS(4 Second of ) and Z (Li+W)-XPS(8 Second of ) satisfies 0≤IZ (Li+W)-XPS(0 Second of ) -Z (Li+W)-XPS(4 Second of ) |≤0.1,0≤|Z (Li+W)-XPS(0 Second of ) -Z (Li+W)-XPS(8 Second of ) ≤0.1.
  3. 3. The positive electrode material according to claim 1, wherein the positive electrode material satisfies that Z (Li+W)-XPS(0 Second of ) is 90% or more, Z (Li+W)-XPS(4 Second of ) is 80% or more, and Z (W)-XPS(8 Second of ) is 80% or more.
  4. 4. The positive electrode material according to claim 1, wherein a chemical formula in the coating layer is Li d W 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 element W 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 W h M m O 2 , wherein b≤ 1.05,0.8≤x≤1, 0≤y+z≤0.2, x+y+z+h= 1,0.0001≤h≤ 0.003,0≤m≤1, and wherein the element F is at least one element selected from Mn and Al, and the element M is at least one element 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 2-5 nm; (2) The matrix 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 with a lithium source, and sintering the mixture to obtain a primary sintered 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, continuously stirring, and reacting a coating element in the coating material with lithium in the re-sintered product to form a coating layer through intermittent gradient temperature reaction to obtain 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, increasing the Ni content in the positive electrode material causes serious phase transition and oxygen release phenomena in the charge and discharge process, and the surface is susceptible to side reaction with the electrolyte, resulting in poor cycle performance and poor thermal stability of the positive electrode material, which limits its wide application. Therefore, there is a need to develop a novel positive electrode material to solve the above problems. 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, the embodiment of the application provides a positive electrode material, which comprises a substrate and a coating layer, wherein the coating layer is coated on the surface of the substrate, the coating layer comprises a Li element and a W element, the positive electrode material meets the conditions that Z (Li+W)-XPS(0 Second of )、Z(Li+W)-XPS(4 Second of ) and Z (Li+W)-XPS(8 Second of ) are both more than 80%, wherein the sum of the atomic weight ratios of the Li atom and the W atom measured after the positive electrode material is etched for 0 seconds by using an X-ray photoelectron spectrometer (XPS) is Z (Li+W)-XPS(0 Second of ), the sum of the atomic weight ratios of the Li atom and the W atom obtained after the positive electrode material is etched for 4 seconds by using XPS is Z (Li+W)-XPS(4 Second of ), and the sum of the atomic weight ratios of the Li atom and the W atom obtained after the positive electrode material is etched for 8 seconds by using XPS is Z (Li+W)-XPS(8 Second of ). In some possible embodiments, the relationship of Z (Li+W)-XPS(0 Second of )、Z(Li+W)-XPS(4 Second of ) to Z (Li+W)-XPS(8 Second of ) satisfies 0≤IZ (Li+W)-XPS(0 Second of )-Z(Li+W)-XPS(4 Second of )|≤0.1,0≤|Z(Li+W)-XPS(0 Second of )-Z(Li+W)-XPS(8 Second of )≤0.1. In some possible embodiments, the positive electrode material satisfies that Z (Li+W)-XPS(0 Second of ) is above 90%, Z (Li+W)-XPS(4 Second of ) is above 80%, and Z (W)-XPS(8 Second of ) is above 80%. In some possible embodiments, the cladding layer has a chemical formula of Li dWeOf, where 0< d <0.5,0< e <0.002,0< f≤2. In some possible embodiments, the mass ratio of the W element in the positive electrode material is 500ppm to 2000ppm. In some possible embodiments, the chemical formula of the positive electrode material is Li bNixCoyFzWhMmO2, wherein b is more than or equal to 0.95 and less than or equal to 1.05,0.8 and less than or equal to x is less than 1,0< y+z is more than or equal to 0.2, x+y+z+h= 1,0.0001 and less than or equal to 0.003,0 and less than or equal to M is less than or equal to 1, F element is at least one of Mn and Al, and M element is at least one of Ca, ti, zr, sr, mg, sb, Y, la. In some possible embodiments, the thickness of the coating layer is 2-5 nm. In some possible embodiments, the matrix 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 provides a preparation method of the positive electrode material, which comprises the steps of mixing an oxide or hydroxide precursor with a lithium source, sintering the mixture to obtain a primary sintered product, crushing and dispersing the primary sintered product, supplementing lithium to the dispe