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CN-122025735-A - Lithium ion secondary battery, battery device, power utilization device, preparation method of positive electrode active material and preparation method of positive electrode plate

CN122025735ACN 122025735 ACN122025735 ACN 122025735ACN-122025735-A

Abstract

The application provides a lithium ion secondary battery, a battery device, an electric device, a preparation method of an anode active material and a preparation method of an anode plate. The lithium ion secondary battery comprises a positive electrode plate, a negative electrode plate and an electrolyte, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises lithium-containing transition metal phosphate particles at least part of the surfaces of which are provided with carbon coating materials, the area ratio of the particles with the particle size of more than or equal to 1 mu m in a section of the positive electrode film layer along the thickness direction of the electrode plate is 30.0-50.0%, and the mass ratio of magnetic substances in the positive electrode film layer is more than or equal to 20ppm and less than or equal to 1980ppm.

Inventors

  • LI XIAOJING
  • LIU HONGYU
  • BIE CHANGFENG
  • JIA XIAOYANG
  • HE SIYUAN
  • NI HUAN
  • LIU NA

Assignees

  • 宁德时代新能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20250507
Priority Date
20250328

Claims (20)

  1. 1. A lithium ion secondary battery is characterized by comprising a positive electrode plate, a negative electrode plate and electrolyte, Wherein the positive pole piece comprises a positive current collector and a positive film layer arranged on at least one side of the positive current collector, The positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises lithium-containing transition metal phosphate particles at least part of the surfaces of which are provided with carbon coating materials, In the section of the positive electrode film layer along the thickness direction of the pole piece, the area occupied ratio of the particles with the particle diameter of more than or equal to 1 mu m is 30.0% -50.0%, and the average equivalent area occupied ratio of the particles with the particle diameter of more than 1 mu m is more than or equal to 0.15% and less than 0.2%.
  2. 2. The lithium ion secondary battery according to claim 1, wherein the area ratio of particles having a particle diameter of 1 μm to 5 μm in a section of the positive electrode film layer in the thickness direction of the electrode sheet is 30.0% to 50.0%.
  3. 3. The lithium ion secondary battery according to claim 1, wherein the area ratio of particles having a particle diameter of 1 μm to 5 μm in a section of the positive electrode film layer in the thickness direction of the electrode sheet is 30.0% to 45.0%.
  4. 4. The lithium ion secondary battery according to claim 1, wherein the area ratio of particles having a particle diameter of 50nm to 200nm in a section of the positive electrode film layer in the thickness direction of the electrode sheet is 3.0% to 15.0%.
  5. 5. The lithium ion secondary battery according to claim 1, wherein the area ratio of particles having a particle diameter of 50nm to 200nm in a section of the positive electrode film layer in the thickness direction of the electrode sheet is 5.0% to 12.0%.
  6. 6. The lithium ion secondary battery according to claim 1, wherein the area ratio of particles having a particle diameter of 50nm to 200nm in a section of the positive electrode film layer in the thickness direction of the electrode sheet is 5.0% to 10.0%.
  7. 7. The lithium ion secondary battery according to claim 1, wherein the mass ratio of the magnetic substance in the positive electrode film layer is 30ppm or more and 1980ppm or less.
  8. 8. The lithium ion secondary battery according to claim 7, wherein the mass ratio of the magnetic substance in the positive electrode film layer is 300ppm or less.
  9. 9. The lithium ion secondary battery according to claim 7, wherein the mass ratio of the magnetic substance in the positive electrode film layer is 30ppm to 200ppm.
  10. 10. The lithium ion secondary battery according to claim 7, wherein, The magnetic substance comprises one or more of elemental iron and Fe 2 P、FeP、γ-Fe 2 O 3 、Fe 2 P 2 O 7 .
  11. 11. The lithium ion secondary battery according to claim 10, wherein, In the positive electrode film layer, the mass content of the simple substance iron is less than 20ppm.
  12. 12. The lithium ion secondary battery according to claim 10, wherein, In the positive electrode film layer, the mass content of the simple substance iron is less than or equal to 15ppm.
  13. 13. The lithium ion secondary battery of claim 1, wherein the lithium-containing transition metal phosphate particles comprise a component having the general formula: Li m Fe x P y O j Q q , wherein Q comprises one or more of Al, na, K, mg, cu, mn, cr, zn, pb, ca, co, ni, sr, nb, V, ti, B, S, si, N, F, cl, br, m is more than or equal to 0.8 and less than or equal to 1.15,0.9 x is less than or equal to 1,0.95 and less than or equal to x is less than or equal to 1,0.95 is less than or equal to.
  14. 14. The lithium ion secondary battery according to claim 1, wherein the positive electrode active material includes titanium element, and the mass content of the titanium element is 1500ppm to 8000ppm based on the total mass of the positive electrode active material.
  15. 15. The lithium ion secondary battery according to claim 14, wherein the positive electrode active material includes titanium element, and the mass content of the titanium element is 2500ppm to 8000ppm based on the total mass of the positive electrode active material.
  16. 16. The lithium ion secondary battery according to claim 14, wherein the positive electrode active material includes titanium element, and the mass content of the titanium element is 2500ppm to 6000ppm based on the total mass of the positive electrode active material.
  17. 17. The lithium ion secondary battery according to claim 1, wherein the mass ratio of the carbon element is 0.9% to 1.8% based on the total mass of the positive electrode active material.
  18. 18. The lithium ion secondary battery according to claim 1, wherein in the cumulative distribution curve of graphitization degree C values obtained by the positive electrode film layer in the laser micro-confocal raman spectrometer surface scanning mode, a median C 50 of graphitization degrees is equal to or greater than 0.9 and equal to or less than 1.3, wherein the graphitization degree C value is I G /I D , wherein I G represents a G peak intensity of a raman spectrum at 1580±100cm -1 , and I D represents a D peak intensity of a raman spectrum at 1350±100cm -1 .
  19. 19. The lithium ion secondary battery according to claim 18, wherein the positive electrode film layer has a graphitization degree C 50 of 0.99 to 1.2 in a graphitization degree C value cumulative distribution curve obtained in a laser micro-confocal raman spectrometer surface scanning mode.
  20. 20. The lithium ion secondary battery according to claim 1, wherein in the cumulative distribution curve of the area of the sphericity of the particles obtained by the section of the positive electrode film layer in the thickness direction of the electrode sheet, the median L A50 of the sphericity is 0.60 to 0.85.

Description

Lithium ion secondary battery, battery device, power utilization device, preparation method of positive electrode active material and preparation method of positive electrode plate The application relates to a split application of China patent application No. 202510578843.8, which is filed on 5-7-2025 and is entitled "lithium ion secondary battery, battery device, power utilization device, preparation method of positive electrode active material and preparation method of positive electrode plate". Cross Reference to Related Applications The present application claims priority from PCT patent application PCT/CN2025/085902 entitled "lithium ion secondary battery, battery device, electrical device, method of producing positive electrode active material, and method of producing positive electrode sheet," filed on 28 at 3 month 2025, the entire contents of which are incorporated herein by reference. Technical Field The application relates to the technical field of lithium ion batteries, in particular to a lithium ion secondary battery, a battery device, an electric device, a preparation method of an anode active material and a preparation method of an anode plate. Background In recent years, lithium ion secondary batteries are widely used in energy storage power supply systems such as hydraulic power, thermal power, wind power and solar power stations, and in various fields such as electric tools, electric bicycles, electric motorcycles, electric automobiles, military equipment, aerospace and the like. With the improvement of the endurance capability and the safety requirement of the electric device in the market, higher requirements are also put on the energy density, the storage performance and the like of the lithium ion secondary battery. However, it is difficult to achieve the above performance improvement in the prior art, which is a technical problem to be solved in the art. Disclosure of Invention The present application has been made in view of the above problems, and an object thereof is to provide a lithium ion secondary battery having both high energy density and good storage performance. The first aspect of the application provides a lithium ion secondary battery, which comprises a positive electrode plate, a negative electrode plate and an electrolyte, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode film layer arranged on at least one side of the positive electrode current collector, the positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises lithium-containing transition metal phosphate particles at least part of the surfaces of which are provided with carbon coating materials, the area ratio of the particles with the particle size of more than or equal to 1 mu m is 30.0-50.0% in a section of the positive electrode film layer along the thickness direction of the plate, and the mass ratio of magnetic substances in the positive electrode film layer is more than or equal to 20ppm and less than or equal to 1980ppm. The embodiment of the application improves the area ratio of large-size particles and simultaneously effectively reduces the content of magnetic substances in the positive electrode film layer, so that the mass ratio of the magnetic substances in the positive electrode film layer is more than or equal to 20ppm and less than or equal to 1980ppm, the compacted density of the pole pieces in the lithium ion secondary battery is improved, and meanwhile, the low self-discharge rate can be maintained, thereby being beneficial to improving the energy density of the battery and being maintained for a long time in the storage process. In any embodiment, the area ratio of the particles with the particle diameter of 1-5 μm in the section of the positive electrode film layer along the thickness direction of the pole piece is 30.0-50.0%. In the section of the positive electrode film layer along the thickness direction of the pole piece, the area ratio of particles with the particle diameter of 1-5 μm is in the range, so that the content of magnetic substances in the battery can be controlled while the compacted density of the pole piece is improved through grading, and the improvement of the energy density of the lithium ion secondary battery and the long-term maintenance in the storage process are facilitated. In any embodiment, the area ratio of the particles with the particle diameter of 1-5 μm in the section of the positive electrode film layer along the thickness direction of the pole piece is 30.0-45.0%. In the section of the positive electrode film layer along the thickness direction of the pole piece, the area ratio of the particles with the particle diameter of 1-5 μm is in the range, so that the compaction density and the capacity storage stability can be improved, meanwhile, the migration distance of lithium ions in the particles can be further considered, the l