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CN-121986390-A - Positive electrode active material and method for producing same

CN121986390ACN 121986390 ACN121986390 ACN 121986390ACN-121986390-A

Abstract

The present invention relates to a lithium metal battery having improved life and stability, comprising a positive electrode, a lithium metal negative electrode, a separator interposed between the positive electrode and the lithium metal negative electrode, and a non-aqueous electrolyte comprising an organic solvent, a lithium salt, and a compound represented by formula I described herein.

Inventors

  • LI RENDE
  • LI TAIRONG
  • JIN ZHONGBI
  • BIAN ZHIYUAN
  • ZHENG YUANZHI
  • LI KANGXUAN
  • ZHENG ZHONGXI
  • Huang Huirun

Assignees

  • 株式会社LG化学

Dates

Publication Date
20260505
Application Date
20241011
Priority Date
20231012

Claims (16)

  1. 1. A positive electrode active material in the form of single particles comprising: Lithium transition metal oxide in the form of single particles, and A first coating portion in the form of a film and a second coating portion in the form of islands, which are formed on the lithium transition metal oxide in the form of single particles, Wherein the first coating portion and the second coating portion each independently contain a cobalt compound containing Co and an oxide containing an element M, wherein M is at least one selected from Zr, al, B, ti, mg, cr, cu, V and W, Wherein the content of Co contained in the first coating portion is higher than the content of Co contained in the second coating portion, and The content of M element contained in the second coating portion is higher than the content of M element contained in the first coating portion.
  2. 2. The positive electrode active material in the form of single particles according to claim 1, wherein a molar ratio (Co 1 :M 1 ) of Co and M elements contained in the first coating portion is 1:0.01 to 0.99.
  3. 3. The positive electrode active material in the form of single particles according to claim 1, wherein a molar ratio of Co and M elements (Co 2 :M 2 ) contained in the second coating portion is 0.01 to 0.99:1.
  4. 4. The single particle form of the positive electrode active material according to claim 1, wherein a molar ratio (M 1 :M 2 ) of the M element contained in the first coating layer portion to the M element contained in the second coating layer portion is 0.001 to 0.99:1.
  5. 5. The positive electrode active material in the form of single particles according to claim 1, wherein Ni content contained in the second coating layer portion is 30 wt% or less based on the total weight of the second coating layer portion.
  6. 6. The single particle form of the positive electrode active material according to claim 1, wherein an average particle diameter (D 50 ) of the single particle form of the positive electrode active material is 0.1 μm to 10 μm.
  7. 7. The single particle form of the positive electrode active material according to claim 1, wherein the single particle form of the positive electrode active material is in a form in which 50 or less of the primary particles composed of 10 or less single crystal grains are agglomerated.
  8. 8. The single particle form of the positive electrode active material according to claim 1, wherein the single particle form of the lithium transition metal oxide is a lithium composite transition metal oxide containing nickel (Ni), cobalt (Co), and manganese (Mn).
  9. 9. The single particle form of the positive electrode active material according to claim 1, wherein the single particle form of the lithium transition metal oxide has a composition represented by the following chemical formula 1: [ chemical formula 1] Li a Ni b Co c Mn d M 1 e O 2 Wherein: M 1 is at least one selected from Al, zr, B, W, mo, cr, nb, mg, hf, ta, la, ti, sr, ba, ce, sn, Y, zn, F, P and S, and A≤a≤ 1.1,0.8≤b <1.0,0< c <0.2,0< d <0.2, 0≤e≤0.1, and b+c+d+e=1.
  10. 10. A method of manufacturing the positive electrode active material according to claim 1, the method comprising the steps of: (A) Preparing a mixture by mixing a lithium transition metal oxide in the form of single particles, a Co-containing raw material and an M-element-containing raw material, wherein M is at least one selected from Zr, al, B, ti, mg, cr, cu, V and W, and (B) The mixture is subjected to a first heat treatment at a temperature of greater than 600 ℃ and less than 800 ℃, and then to a second heat treatment at a temperature of 400 ℃ to 600 ℃.
  11. 11. The method for producing a positive electrode active material according to claim 10, wherein the Co-containing raw material is at least one selected from the group consisting of Co(OH) 2 、Co 2 O 3 、CoCl 2 、Co(NO 3 ) 2 、Co(CH 3 CO 2 ) 2 and a hydrate thereof.
  12. 12. The method for manufacturing a positive electrode active material according to claim 10, wherein in the step (a), the lithium transition metal oxide in a single particle form is mixed with the Co-containing raw material in a molar ratio of 1:0.01 to 0.05.
  13. 13. The method for manufacturing a positive electrode active material according to claim 10, wherein in the step (a), the raw material containing M element is mixed in an amount of 500 ppm to 5000 ppm based on the total weight of the lithium transition metal oxide in the form of single particles.
  14. 14. The method for producing a positive electrode active material according to claim 10, wherein the mixing in the step (a) is dry mixing.
  15. 15. The method for manufacturing a positive electrode active material according to claim 10, wherein the first heat treatment in the step (B) is performed under an oxygen atmosphere.
  16. 16. The method for manufacturing a positive electrode active material according to claim 10, wherein the second heat treatment in the step (B) is performed under an oxygen atmosphere.

Description

Positive electrode active material and method for producing same Cross Reference to Related Applications The present application claims the benefit of priority from korean patent application No. 10-2023-0136137 filed on 10/12 of 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field The present invention relates to a positive electrode active material in the form of single particles and a method for producing the same. Background Recently, as technology development and demand for mobile devices and electric vehicles increase, demand for secondary batteries as energy sources has rapidly increased. Among secondary batteries, lithium secondary batteries having high energy density and voltage, long cycle life, and low self-discharge rate have been commercialized and widely used. A lithium secondary battery generally consists of a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode and the negative electrode include an active material capable of inserting and extracting lithium ions. As a positive electrode active material of a lithium secondary battery, lithium transition metal oxides such as lithium cobalt oxide (e.g., liCoO 2), lithium nickel oxide (e.g., liNiO 2), lithium manganese oxide (e.g., liMnO 2 or LiMn 2O4), and lithium iron phosphate oxide (e.g., liFePO 4) have been developed, and lithium composite transition metal oxides containing two or more transition metals such as Li [ Ni aCobMnc]O2、Li[NiaCobAlc]O2 and Li [ Ni aCobMncAld]O2 ] have been recently developed and widely used. Meanwhile, a positive electrode active material used in a lithium secondary battery generally has the form of spherical secondary particles formed by agglomerating hundreds of fine primary particles having a submicron size. However, the positive electrode active material in the form of secondary particles has a problem in that cracks occur in the secondary particles during repeated charge/discharge, thereby causing various side reactions and deteriorating battery characteristics. In order to solve this problem, development of a cathode active material in a single particle form is actively being conducted, but when manufacturing a cathode active material in a single particle form, calcination at a higher temperature than when manufacturing a cathode active material in a secondary particle form is required, which results in a problem that the ratio of NiO reduction layers on the particle surfaces increases. Meanwhile, when the ratio of the NiO reduction layer increases on the surface of the cathode active material, problems such as an increase in resistance, a decrease in capacity, and a decrease in output of the battery occur, and thus a surface treatment technique capable of controlling the NiO reduction layer is required. Disclosure of Invention Technical problem An object of the present invention is to provide a positive electrode active material capable of realizing a battery having improved discharge capacity, lifetime, resistance, output, gas performance, and the like by controlling a NiO reduction layer, and a method for manufacturing the same. Technical proposal In order to achieve the above object, the present invention provides a positive electrode active material and a method for manufacturing the same. (1) The present invention provides a single particle form of a positive electrode active material comprising a single particle form of a lithium transition metal oxide, and a film form of a first coating portion and an island form of a second coating portion formed on the single particle form of the lithium transition metal oxide, wherein the first coating portion and the second coating portion each independently contain a cobalt compound containing Co and an oxide containing M element (wherein M is at least one selected from Zr, al, B, ti, mg, cr, cu, V and W), wherein a content of Co contained in the first coating portion is higher than a content of Co contained in the second coating portion, and a content of M element contained in the second coating portion is higher than a content of M element contained in the first coating portion. (2) The present invention provides the positive electrode active material in a single particle form according to the above (1), wherein the molar ratio (Co 1:M1) of Co and M elements contained in the first coating portion is 1:0.01 to 0.99. (3) The present invention provides the positive electrode active material in a single particle form according to the above (1) or (2), wherein the molar ratio (Co 2:M2) of Co and M elements contained in the second coating portion is 0.01 to 0.99:1. (4) The present invention provides the positive electrode active material in a single particle form according to any one of the above (1) to (3), wherein a molar ratio (M 1:M2) of the M element contained in the first coating portion to the M element contained in the second coating portion is 0.001 to 0.99:1.