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CN-122000350-A - Positive electrode active material, preparation method thereof and battery

CN122000350ACN 122000350 ACN122000350 ACN 122000350ACN-122000350-A

Abstract

The application discloses a positive electrode active material, a preparation method thereof and a battery, wherein the positive electrode active material comprises monocrystalline particles, the positive electrode active material comprises nickel-cobalt-manganese ternary material, the long-range order eta of the positive electrode active material is 0.85-0.96, D S is the average size of the single crystal particles, and D x is the average subgrain size of single long-range ordered crystals calculated in the X-ray diffraction refinement of the positive electrode active material. The positive electrode active material has good internal crystallinity, consistent arrangement direction and low cation disorder degree, is beneficial to reducing the impedance of the positive electrode active material and improving the capacity exertion and the multiplying power performance of the positive electrode active material, and more mainly is beneficial to improving the diffusion kinetics of lithium ions and inhibiting heterogeneous reaction, further relieves the local lattice anisotropic strain in the charge and discharge process, reduces the generation risk of microcracks and obviously improves the circulation stability of the positive electrode active material.

Inventors

  • LIU YUN
  • YAN PENG
  • GAO DONGLI
  • Shao Zongpu
  • WU LIANGCE
  • LIU YAFEI
  • ZHANG XUEQUAN
  • CHEN YANBIN

Assignees

  • 北京当升材料科技股份有限公司

Dates

Publication Date
20260508
Application Date
20260331

Claims (15)

  1. 1. The positive electrode active material is characterized by comprising monocrystalline particles, wherein the positive electrode active material comprises a nickel-cobalt-manganese ternary material, and the long-range order eta of the positive electrode active material is 0.85-0.96; Wherein, the ; D S is the average size of the single crystal particles; d x is the average subgrain size of single long range ordered crystals calculated in the positive electrode active material X-ray diffraction refinement.
  2. 2. The positive electrode active material according to claim 1, wherein the positive electrode active material has a long-range order η of 0.88 to 0.93.
  3. 3. The positive electrode active material according to claim 1, wherein 0.8 μm or less D s μm or less 1.8 μm; 0.7μm≤D x ≤1.7μm。
  4. 4. the positive electrode active material according to claim 1, wherein the positive electrode active material has a cation order μ of 95% to 99%, optionally 95.5% to 98.5%; Wherein, the ; N (Nio) is the number of Ni atoms mixed and arranged at Li position in the positive electrode active material, and n (Nim) is the total number of Ni atoms in the crystal lattice of the positive electrode active material.
  5. 5. The positive electrode active material according to claim 1, wherein the number of equivalent sheet layers N (003) of the (003) plane of the positive electrode active material is 160 to 240, the number of equivalent sheet layers N (104) of the (104) plane of the positive electrode active material is 250 to 400, D (003) is the average thickness perpendicular to the (003) plane direction in the positive electrode active material unit cell, in nm, D (003) is the interplanar spacing of the (003) plane in the positive electrode active material unit cell, in nm; D (104) is the average thickness in nm perpendicular to the (104) crystal plane direction in the positive electrode active material unit cell, and D (104) is the interplanar spacing in nm of the (104) crystal plane in the positive electrode active material unit cell.
  6. 6. The positive electrode active material according to any one of claims 1 to 5, characterized by satisfying a chemical formula: Li 1+a Ni u Co v Mn w M m J n O 2+b ; Wherein, -0.05≤a≤ 0.3,0.8≤u≤1, 0≤v≤0.2, 0≤w≤0.2, 0< m≤ 0.02,0≤n≤4, -0.05≤b≤0.3, M comprises at least one of Zr, al, ce, ba, mg, sr, J comprises at least one of Al, zr, F, B, cl, br, I, S, W, la, P.
  7. 7. The positive electrode active material according to claim 6, wherein a ratio n (M)/n (ni+co+mn) of a molar amount of the M element to a sum of molar amounts of the nickel element, the cobalt element, and the manganese element in the positive electrode active material is greater than 0.005.
  8. 8. The positive electrode active material according to claim 6, wherein a molar amount of M element on a surface of the positive electrode active material is larger than a molar amount of M element inside the positive electrode active material.
  9. 9. A method for producing the positive electrode active material according to any one of claims 1 to 8, comprising: Mixing a nickel source, a cobalt source, a manganese source, a precipitator and a complexing agent, and then performing coprecipitation reaction to obtain a precursor; mixing the precursor, a first lithium source and a first M source, and then performing first sintering treatment to obtain a first sintering material, wherein the ratio of the molar quantity of lithium elements corresponding to the first lithium source to the total molar quantity of nickel elements, cobalt elements and manganese elements in the precursor is 0.8-0.95; Mixing the first sintering material and a second lithium source and then performing second sintering treatment to obtain a second sintering material; And mixing the second sintering material with a second M source, and then performing third sintering treatment to obtain the positive electrode active material.
  10. 10. The method according to claim 9, wherein a ratio of a sum of molar amounts of lithium elements corresponding to the first lithium source and the second lithium source to a total molar amount of nickel element, cobalt element, and manganese element in the precursor is 1.02 to 1.10.
  11. 11. The method according to claim 9 or 10, wherein the temperature of the first sintering treatment is 700 ℃ to 900 ℃ for 6h to 12h, and/or, The temperature of the second sintering treatment is 700-850 ℃ and the time is 6-12 h.
  12. 12. The method of claim 9 or 10, wherein the molar amount of M element corresponding to the second M source is greater than the molar amount of M element corresponding to the first M source.
  13. 13. The method according to claim 9 or 10, wherein the temperature of the third sintering treatment is 500 ℃ to 700 ℃ for 3h to 10h.
  14. 14. The method of claim 9, further comprising mixing the positive electrode active material and a J source and then performing a fourth sintering process, wherein the fourth sintering process is performed at a temperature of 200 ℃ to 500 ℃ for a time of 3h to 10h.
  15. 15. A battery comprising a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer positioned on at least one side of the positive electrode current collector, and the positive electrode active material layer comprises the positive electrode active material according to any one of claims 1 to 8 or the positive electrode active material prepared by the method according to any one of claims 9 to 14.

Description

Positive electrode active material, preparation method thereof and battery Technical Field The application relates to the technical field of lithium batteries, in particular to a positive electrode active material, a preparation method thereof and a battery. Background With the vigorous development of the new energy automobile industry, the power battery technology is updated and iterated continuously, higher requirements are put on the performance of the positive electrode active material, and the development of the high-performance positive electrode active material is a key point for promoting the progress of the industry. In various technical routes, the single-crystal ternary material gradually becomes a research and development hot spot by virtue of the characteristics of high particle strength, high gram capacity, excellent thermal stability and cycle performance and the like. The monocrystal ternary material has complete structure, high grain strength and high compaction density, avoids the problem of stacking grain boundaries and grains common in the traditional secondary grains, is favorable for realizing better capacity exertion, and remarkably reduces microcracks and pulverization phenomena of the positive electrode active material in the circulation process, thereby prolonging the cycle life of the battery. Meanwhile, the monocrystal ternary material has smaller specific surface area and lower porosity, and has the same advantages in the aspects of inhibiting gas production, thermal stability, high-temperature circulation performance and the like. However, single crystal ternary materials, although having better structural stability, are still susceptible to complex failure modes under high SOC conditions and high voltage conditions. It should be noted that the foregoing statements are merely to provide background information related to the present disclosure and may not necessarily constitute prior art. Disclosure of Invention In a first aspect of the present application, the present application provides a positive electrode active material, the positive electrode active material comprising single crystal particles, the positive electrode active material comprising a nickel cobalt manganese ternary material, the positive electrode active material having a long range order η of 0.85 to 0.96, wherein,D S is the average size of the single crystal particles, and D x is the average subgrain size of single long-range ordered crystals calculated in the X-ray diffraction refinement of the positive electrode active material. The positive electrode active material has good internal crystallinity, consistent arrangement direction and low cation disorder degree, is beneficial to reducing the impedance of the positive electrode active material and improving the capacity exertion and the multiplying power performance of the positive electrode active material, and more mainly is beneficial to improving the diffusion kinetics of lithium ions and inhibiting heterogeneous reaction, further relieves the local lattice anisotropic strain in the charge and discharge process, reduces the generation risk of microcracks and obviously improves the circulation stability of the positive electrode active material. In some embodiments, the positive electrode active material has a long range order η of 0.88 to 0.93. Therefore, dislocation and subgrain boundary in the crystal of the positive electrode active material are eliminated, and the structure and electrochemical stability are improved. In some embodiments, 0.8 μm or less D s≤1.8μm;0.7μm≤Dx. Ltoreq.1.7 μm. Therefore, the long-range order degree of the positive electrode active material is improved, the structural distortion is reduced, and the multiplying power performance of the positive electrode active material is improved. In some embodiments, the positive electrode active material has a cationic order μ of 95% to 99%, optionally 95.5% to 98.5%, wherein,N (Nio) is the number of Ni atoms mixed and arranged at Li position in the positive electrode active material, and n (Nim) is the total number of Ni atoms in the crystal lattice of the positive electrode active material. The lithium ion intercalation and deintercalation method is beneficial to reducing the kinetic energy barrier during the intercalation and deintercalation of lithium ions, thereby improving the multiplying power performance and the low-temperature discharge capability of the battery, secondly, is beneficial to reducing the lattice mismatch degree between a transition metal layer and a lithium layer, reducing the anisotropic stress inside the positive electrode active material in the repeated charge and discharge process, effectively restraining the generation of lattice slip and intra-crystal cracks, reducing the side reaction caused by continuously exposing the fresh surface to electrolyte, further improving the structural integrity and the interface stability of single crystal particles in the ci