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KR-20260065018-A - positive electrode active material for sodium secondary battery, method for preparing the same and sodium secondary battery including the same

KR20260065018AKR 20260065018 AKR20260065018 AKR 20260065018AKR-20260065018-A

Abstract

One embodiment of the present invention provides a positive electrode active material for a sodium secondary battery comprising P2-type layered oxide particles and O3-type layered oxide particles.

Inventors

  • 박아람
  • 이동욱

Assignees

  • 주식회사 에코프로비엠

Dates

Publication Date
20260508
Application Date
20241031

Claims (11)

  1. A positive electrode active material for a sodium secondary battery comprising P2-type layered oxide particles and O3-type layered oxide particles.
  2. In paragraph 1, The above P2-type layered oxide particles comprise at least one doping metal selected from Ca and Cu, and are a positive electrode active material for a sodium secondary battery.
  3. In paragraph 1, The above O3-type layered oxide particles comprise at least one doping metal selected from Ca and Cu, and are a positive electrode active material for a sodium secondary battery.
  4. In paragraph 1, A positive electrode active material for a sodium secondary battery, wherein the above P2-type layered oxide is represented by the following chemical formula 1 and the above O3-type layered oxide is represented by the following chemical formula 2: [Chemical Formula 1] Na a1-v1 Ca v1 [TM 1-x1-y1 Cu x1 M y1 ]O 2 In the above chemical formula 1, TM is at least one selected from Ni, Fe, Mn and Co, and M is at least one selected from P, Sr, Ba, Ti, Zr, Al, W, Ce, Hf, Ta, Cr, F, Mg, Cr, V, Fe, Zn, Si, Y, Ga, Sn, Mo, Ge, Nd, B, Nb, Gd and Cu, and may be 0.6<a1<0.8, 0≤v1≤0.1, 0≤x1≤0.1, 0≤y1≤0.1, 0.8≤1-x1-y1≤1. [Chemical Formula 2] Na a2-v2 Ca v2 [TM 1-x2-y2 Cu x2 M y2 ]O 2 In the above chemical formula 2, TM is at least one selected from Ni, Fe, Mn and Co, and M is at least one selected from P, Sr, Ba, Ti, Zr, Al, W, Ce, Hf, Ta, Cr, F, Mg, Cr, V, Fe, Zn, Si, Y, Ga, Sn, Mo, Ge, Nd, B, Nb, Gd and Cu, and may be 0.8≤a2≤1.2, 0≤v2≤0.1, 0≤x2≤0.1, 0≤y2≤0.1, and 0.8≤1-x2-y2≤1.
  5. In paragraph 1, A positive electrode active material for a sodium secondary battery, wherein the above P2-type layered oxide particles and O3-type layered oxide particles are included in a weight ratio of 8:2 to 2:8.
  6. Step of preparing P2-type layered oxide particles; Step of preparing O3-type layered oxide particles; and A method for manufacturing a positive electrode active material for a sodium secondary battery, comprising the step of mixing the above P2-type layered oxide particles and the above O3-type layered oxide particles.
  7. In paragraph 6, A method for manufacturing a positive electrode active material for a sodium secondary battery, wherein the step of preparing the above-mentioned P2-type layered oxide particles includes a process of doping at least one selected from Ca and Cu.
  8. In paragraph 6, A method for manufacturing a positive electrode active material for a sodium secondary battery, wherein the step of preparing the above O3-type layered oxide particles includes a process of doping at least one selected from Ca and Cu.
  9. In paragraph 6, A method for manufacturing a positive electrode active material for a sodium secondary battery, wherein the above mixing step involves mixing the P2-type layered oxide particles and the O3-type layered oxide particles in a weight ratio of 8:2 to 2:8.
  10. A cathode for a sodium secondary battery comprising the cathode active material of claim 1.
  11. Sodium secondary battery comprising the positive electrode of claim 10.

Description

Positive electrode active material for sodium secondary battery, method for preparing the same and sodium secondary battery including the same The present invention relates to a positive electrode active material for a sodium secondary battery, a method for manufacturing the same, and a sodium secondary battery comprising the same. Lithium-ion rechargeable batteries have been widely used as energy storage devices in various fields of electronic technology. Recently, with the surge in demand for lithium-ion batteries, sodium-ion rechargeable batteries are attracting attention as a replacement for lithium, an expensive metal. Because sodium-ion rechargeable batteries utilize an insertion/extraction reaction operating principle similar to that of lithium-ion batteries, they are one of the next-generation materials with high potential for application as rechargeable batteries. Layered transition metal oxides are typically used as cathode active materials for sodium-ion secondary batteries because they possess a simple structure, excellent electrochemical performance, and are easy to synthesize. Generally, O3-type layered oxides have a higher energy density compared to P2-type layered oxide particles, but they suffer from reduced cycle stability due to larger structural changes during the charge-discharge process. Conversely, while P2-type layered oxides offer relatively superior cycle stability, their low sodium content results in low initial capacity, making commercial application difficult. There is an attempt to develop a product with excellent initial capacity and lifespan characteristics by applying a mixture of P2-type oxide particles and O3-type oxide particles, which provides a relatively high discharge capacity through the O3-type layered oxide and suppresses structural changes caused by the release of a relatively large amount of sodium ions through the P2-type layered oxide. However, it is difficult to secure the desired battery performance with the application of a simple mixed phase alone. Furthermore, an improved method is required to stabilize the individual structures of P2-type oxide particles and O3-type oxide particles. The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art to which the present invention pertains. Throughout the specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, the singular form includes the plural form unless specifically stated otherwise in the text. One embodiment of the present invention provides a positive electrode active material for a sodium secondary battery comprising P2-type layered oxide particles and O3-type layered oxide particles. Specifically, P2-type layered oxides have excellent lifespan characteristics due to structural stability but have the disadvantage of low initial capacity due to low Na content. Conversely, O3-type layered oxides have high initial capacity due to high Na content but have poor structural stability and are known to have the disadvantage of low Na migration speed and poor lifespan characteristics due to the relatively small size of the octahedral sites where Na can be located within the structure. The present invention provides a positive electrode active material that maintains the advantages of each particle and improves its disadvantages by mixing P2-type and O3-type layered oxide particles. As in one embodiment, the P2-type layered oxide particles may include at least one doping metal selected from Ca and Cu. Specifically, in the present invention, electrochemical performance can be improved by applying a dopant composition optimized for structural stabilization of the P2-type oxide particles, and for example, the P2-type oxide particles may include a Ca-doping metal, the P2-type oxide particles may include a Cu-doping metal, and the P2-type oxide particles may include both Ca and Cu-doping metals. The above O3-type layered oxide particles may include at least one doping metal selected from Ca and Cu. Specifically, in the present invention, electrochemical performance can be improved by applying a dopant composition optimized for structural stabilization of th