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KR-20260063520-A - POSITIVE ELECTRODE FOR RECHARGEABLE LITHIUM BATTERY AND RECHARGEABLE LITHIUM BATTERY INCLUDING THE SAME

KR20260063520AKR 20260063520 AKR20260063520 AKR 20260063520AKR-20260063520-A

Abstract

The invention relates to a positive electrode for a lithium secondary battery and a lithium secondary battery including the same, wherein the positive electrode for the lithium secondary battery comprises a current collector; and a positive electrode active material layer located on the current collector, wherein the positive electrode active material layer comprises a first active material layer in contact with the current collector and a second active material layer located on the first active material layer, wherein the porosity of the second active material layer is 5% to 20% greater than the porosity of the first active material layer, and wherein the first active material layer comprises a secondary particle positive electrode active material, and the second active material layer comprises a single particle positive electrode active material.

Inventors

  • 모리사와 나오야

Assignees

  • 삼성에스디아이 주식회사

Dates

Publication Date
20260507
Application Date
20241030

Claims (14)

  1. Current collector; and It includes a positive active material layer located in the above current collector, and The positive active material layer comprises a first active material layer in contact with the current collector and a second active material layer located on the first active material layer. The porosity of the second active material layer is 5% to 20% greater than the porosity of the first active material layer, and The above first active material layer includes a secondary particle positive electrode active material, and The above second active material layer comprises a single particle positive active material, for a lithium secondary battery.
  2. In paragraph 1, A positive electrode for a lithium secondary battery having a porosity of the second active material layer that is 15% to 20% greater than the porosity of the first active material layer.
  3. In paragraph 1, A positive electrode for a lithium secondary battery, wherein the porosity of the first active material layer and the second active material layer is 10% to 30%.
  4. In paragraph 1, A positive electrode for a lithium secondary battery having a porosity of 20% to 30% of the second active material layer.
  5. In paragraph 4, A positive electrode for a lithium secondary battery having a porosity of 25% to 30% of the second active material layer.
  6. In paragraph 1, A positive electrode for a lithium secondary battery, wherein the porosity of the first active material layer is 10% to 25%.
  7. In paragraph 6, A positive electrode for a lithium secondary battery having a porosity of 10% to 15% of the first active material layer.
  8. In paragraph 1, The above secondary particle is a positive electrode for a lithium secondary battery formed by assembling primary particles.
  9. In paragraph 1, A positive electrode for a lithium secondary battery, wherein the average particle size (D50) of the above secondary particles is 1 μm to 50 μm.
  10. In paragraph 8, A positive electrode for a lithium secondary battery, wherein the average particle size (D50) of the primary particles is 50 nm to 1 µm.
  11. In paragraph 1, A positive electrode for a lithium secondary battery, wherein the first active material layer further comprises a single particle positive electrode active material.
  12. In Paragraph 11, A positive electrode for a lithium secondary battery, wherein the first active material layer comprises the secondary particle positive electrode active material and the single particle positive electrode active material in a weight ratio of 5:5 to 9:1.
  13. In paragraph 1, A positive electrode for a lithium secondary battery, wherein the thickness ratio of the first active material layer and the second active material layer is 4:6 to 9:1.
  14. The positive electrode of any one of paragraphs 1 to 13; cathode; and Non-aqueous electrolytes A lithium secondary battery including

Description

Positive electrode for rechargeable lithium battery and rechargeable lithium battery including the same This invention relates to a positive electrode for a lithium secondary battery and a lithium secondary battery containing the same. With the recent rapid proliferation of battery-powered electronic devices such as mobile phones, laptop computers, and electric vehicles, the demand for high-energy-density, high-capacity rechargeable batteries is increasing rapidly. Accordingly, research and development to improve the performance of lithium-ion batteries is actively underway. A lithium secondary battery is a battery comprising a positive electrode and a negative electrode containing an active material capable of lithium ion intercalation and deintercalation, and an electrolyte, and produces electrical energy through oxidation and reduction reactions when lithium ions are intercalated/deintercalated from the positive electrode and the negative electrode. FIG. 1 is a cross-sectional view schematically showing an anode according to one embodiment. FIGS. 2 to 5 are cross-sectional views schematically showing a lithium secondary battery according to one embodiment. Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below. Unless otherwise specifically stated in this specification, when a part such as a layer, film, region, plate, etc. is described as being "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between. Unless otherwise specified in this specification, a singular form may also include a plural form. Additionally, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B." In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc. Unless otherwise defined in this specification, the particle size may be the average particle size. Additionally, the particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. The average particle size (D50) may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. Alternatively, the average particle size (D50) value may be obtained by measuring using a measuring device utilizing dynamic light scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Alternatively, it may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound of about 28 kHz at an output of 60 W, and then the average particle size (D50) at 50% of the particle size distribution in the measuring device can be calculated. In one embodiment, the average particle size can be measured by the various methods described above, for example, using a particle size analyzer. In one embodiment, the thickness may be measured using an SEM or TEM image of a cross-section, but is not limited thereto and may be measured by any method capable of measuring thickness in the field. The thickness may be an average thickness. In this specification, soft carbon refers to a graphitizable carbon material that can be graphitized by heat treatment at a high temperature, e.g., 2800°C, and hard carbon refers to a non-graphitizable carbon material that is not graphitized by heat treatment. Soft carbon and hard carbon are widely known in the art. In one embodiment, crystalline carbon and amorphous carbon can be classified by X-ray diffraction analysis. The crystalline carbon includes natural graphite and artificial graphite. Natural graphite refers to naturally occurring graphite obtained by separation from minerals, and has a d002 of 3.350 Å to 3.360 Å when analyzed by X-ray diffraction, and artificial graphite refers to graphite produced by graphitization, and has a d002 of 3.355 Å to 3.365 Å when analyzed by X-ray diffraction. Amorphous carbon has a d002 of 3.34 Å or less when analyzed by X-ray diffraction. The X-ray diffraction analysis (XRD) can be performed using an X-ray diffraction analyzer, such as X'Pert (manufacturer: Malvern Panalytical), with CuKα rays as the target line, and the monochromator can be removed to improve peak intensity resolution. The measurement conditions ma