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KR-20260064433-A - Lithium-ion secondary battery cathode material having spinel nanocomposite structure and method for manufacturing the same

KR20260064433AKR 20260064433 AKR20260064433 AKR 20260064433AKR-20260064433-A

Abstract

The positive electrode active material for a lithium secondary battery according to the present invention comprises secondary particles composed of a group of primary particles, wherein the primary particles have a spinel (Fd3m) structure and a layered structure ( It includes a nanocomposite in which the structure is mixed at the nano scale. Spinel structures have high structural stability but have the problem of low initial capacity. However, the cathode active material according to the present invention proposes a nanocomposite cathode active material in which a layered structure and a spinel structure are mixed at the nanoscale, thereby providing higher structural stability and improved electrochemical performance than existing single-structure cathode materials without capacity degradation. Furthermore, by introducing a nanocomposite structure including a spinel structure, structural stability is strengthened and deformation during the charging and discharging process is minimized, while simultaneously providing a three-dimensional lithium ion diffusion path to improve lithium ion mobility and enhance rate capability and high-speed charging and discharging performance.

Inventors

  • 박장욱
  • 최경란

Assignees

  • 주식회사 배터리솔루션

Dates

Publication Date
20260507
Application Date
20250207
Priority Date
20241031

Claims (16)

  1. A positive electrode active material for a lithium secondary battery comprising secondary particles composed of a group of multiple primary particles, wherein the primary particles have a spinel (Fd3m) structure and a layered structure ( A cathode active material for a lithium secondary battery comprising a nanocomposite in which the structure is mixed at the nano scale.
  2. In paragraph 1, A positive electrode active material for a lithium secondary battery in which electron diffraction spots S(a, a, a + 2) and S(b, b, b - 2) are observed in SAED electron diffraction images.
  3. In paragraph 2, A positive electrode active material for a lithium secondary battery, wherein the diffraction peak intensity of the L(0, -1, -2-3(m-1)) plane and S(a, a, a+2) plane obtained from the SAED electron diffraction image is I(L(0, -1, -2-3(m-1))) > I(S(a, a, a+2)), and the diffraction peak intensity of the L(0, 1, 2+3(n-1)) plane and S(b, b, b-2) plane obtained from the SAED electron diffraction image is I(L(0, 1, 2+3(n-1))) > I(S(b, b, b-2)).
  4. In paragraph 1, A positive electrode active material for a lithium secondary battery, wherein the maximum length passing through the center of the cross-sectional area of the region where the spinel structure is formed is 1 nm to 100 nm, and the cross-sectional area of the region where the spinel structure is formed is 1 nm² to 10,000 nm².
  5. In paragraph 1, The above nanocomposite is provided on the interior or surface of the primary particle and is a positive electrode active material for a lithium secondary battery provided on the interior or surface of the secondary particle.
  6. In paragraph 1, The above nanocomposite is a positive electrode active material for a lithium secondary battery that is observed before the start of the positive electrode active material charge/discharge cycle.
  7. In paragraph 1, The above nanocomposite is a positive electrode active material for a lithium secondary battery that improves the rate capability characteristics of the positive electrode material by providing a three-dimensional Li + transport pathway in a charged state using the above positive electrode material.
  8. In paragraph 1, The above nanocomposite observed before the charge-discharge cycle is found in the charge state and after the charge-discharge cycle, and the nanocomposite found inside the primary particle after the charge-discharge cycle is a positive electrode active material for a lithium secondary battery that is distinguished from the spinel impurity formed on the surface of the secondary particle due to the degradation of the positive electrode during the charge-discharge cycle.
  9. In paragraph 1, The above primary particles of the positive electrode active material include nickel (Ni), M1 and M2, and The above M1 is composed of at least one of cobalt (Co), manganese (Mn), and aluminum (Al), and A positive electrode active material for a lithium secondary battery, wherein the nickel (Ni) is included in an amount of 50 mol% or more, and the M2 is included as a doping element in an amount of 0.05 to 10 mol%.
  10. In Paragraph 9, The above M2 is a positive electrode active material for a lithium secondary battery comprising one or more of cobalt (Co), manganese (Mn), titanium (Ti), magnesium (Mg), tantalum (Ta), niobium (Nb), tungsten (W), molybdenum (Mo), antimony (Sb), tellurium (Te), tin (Sn), ruthenium (Ru), boron (B), hafnium (Hf), gallium (Ga), germanium (Ge), chromium (Cr), vanadium (V), copper (Cu), calcium (Ca), zinc (Zn), barium (Ba), strontium (Sr), aluminum (Al), and zirconium (Zr).
  11. In Paragraph 10, The above-described positive active material is obtained by mixing a composite metal hydroxide A(OH) 2 precursor with the above-described M2 and performing high-temperature heat treatment, wherein the above-described A is at least one of Ni, Co, Mn, and Al, and is a positive active material for a lithium secondary battery.
  12. In Paragraph 10, The above-described positive electrode active material is obtained by mixing the M2-doped composite metal hydroxide M2-doped A(OH) 2 precursor with a lithium raw material and performing high-temperature heat treatment, wherein A is any one of Ni, Co, Mn, and Al, and is a positive electrode active material for a lithium secondary battery.
  13. In Paragraph 10, The above-described positive electrode active material is obtained by mixing a composite metal hydroxide M2-coated A(OH) 2 precursor, in which M2 is coated by a wet method, with a lithium raw material and performing high-temperature heat treatment, wherein A is any one of Ni, Co, Mn, and Al, and is a positive electrode active material for a lithium secondary battery.
  14. In Paragraph 10, The above-mentioned positive electrode active material is obtained by adding a lithium raw material and M2 to either a precursor of M2-doped AM(OH) 2 or M2-coated A(OH) 2 and performing high-temperature heat treatment, wherein A is any one of Ni, Co, Mn, and Al, and is a positive electrode active material for a lithium secondary battery.
  15. In Paragraph 10, The above-mentioned positive active material is a positive active material for a lithium secondary battery in which an intraparticle concentration gradient is formed in Ni, Co, or Mn.
  16. In Paragraph 10, The above-mentioned positive electrode active material is a positive electrode active material for a lithium secondary battery obtained by mixing either the above-mentioned composite metal hydroxide A(OH) 2 precursor or the wet-doped composite metal hydroxide A(OH) 2 precursor with a lithium raw material and performing a first calcination with high temperature heat treatment, and performing a second calcination with the addition of a dry dopant and performing an additional high temperature heat treatment.

Description

Lithium-ion secondary battery cathode material having spinel nanocomposite structure and method for manufacturing the same The present invention relates to a positive electrode active material for a lithium-ion secondary battery, and more specifically, to a positive electrode active material for a lithium-ion secondary battery having a nanocomposite structure in which a spinel structure and a layered structure are mixed at the nanoscale, and a method for manufacturing the same. Lithium-ion rechargeable batteries are widely used in various electronic devices, electric vehicles, and energy storage systems (ESS) due to their high energy density and long lifespan characteristics. One of the key factors determining the performance of lithium-ion rechargeable batteries is the cathode active material; generally, layered oxides or spinel oxides containing transition metals such as nickel (Ni), cobalt (Co), and manganese (Mn) are used. Conventional high-nickel (high-Ni) based cathode active materials can provide high capacity, but structural instability during charging and discharging can lead to reduced lifespan and degradation. In particular, layered structures are prone to particle cracking due to severe structural deformation during charging and discharging. When cracking occurs, electrolyte penetration into the particles leads to degradation of the primary particle surfaces both inside and outside the secondary particles. This significantly impairs battery performance due to issues such as reduced electronic conductivity and increased interfacial resistance. Research is underway to partially introduce spinel structures as a solution to this problem. Spinel structures can improve conductivity by providing three-dimensional lithium ion diffusion pathways and reduce deformation during charging and discharging by providing structural stability. However, using only spinel structures results in a problem of low initial capacity, so technology is required to achieve optimal performance through a combination with layered structures. Conventionally, the spinel structure was regarded as a trace of degradation in layered cathode materials. The spinel structure is thermodynamically more stable than the layered structure, and it develops as a trace of cathode material degradation at the surface of the secondary particles where the cathode material secondary particles come into contact with the electrolyte. Figures 1 and 2 are TEM (Transmission Electron Microscopy) images to explain the characteristics of a cathode material having a layered & spinel nanocomposite structure according to the present embodiment. Figure 3 is a graph showing the diffraction peak intensity of the layered structure and the spinel structure. Figure 4 is an SEM image of a Mo wet-doped [Ni 0.98 Co 0.01 Mn 0.01 ](OH) 2 precursor according to one embodiment of the present invention. Figure 5 is a TEM image showing the crystal structure of Mo wet-doped Li[Ni 0.98 Co 0.01 Mn 0.01 ] O2 . Figure 6 is a TEM image showing the crystal structures of Mo wet-doped Li[Ni 0.98 Co 0.01 Mn 0.01 ] O2 and ordinary Li[Ni 0.98 Co 0.01 Mn 0.01 ] O2 . Figure 7 is an XRD analysis graph showing the crystal structures of Mo wet-doped Li[Ni 0.98 Co 0.01 Mn 0.01 ] O2 and ordinary Li[Ni 0.98 Co 0.01 Mn 0.01 ] O2 . Figure 8 is a TEM image showing the crystal structure of Mo wet-doped Li[Ni 0.98 Co 0.01 Mn 0.01 ] O2 after 100 cycles. Figure 9 is a TEM image showing the crystal structure of Mo wet-doped Li[Ni 0.98 Co 0.01 Mn 0.01 ] O2 after charging to 4.3V. Figures 10 and 11 are TEM images showing the crystal structures of Ta two-step doped Li[Ni 0.94 Co 0.04 Mn 0.02 ] O2 and ordinary Li[Ni 0.94 Co 0.04 Mn 0.02 ] O2 . Figure 12 is an SEM image of a Co wet-coated [Ni 0.9 Co 0.05 Mn 0.05 ](OH) 2 precursor. Figure 13 is a cross-sectional TEM-EDS image of a Co wet-coated [Ni 0.9 Co 0.05 Mn 0.05 ](OH) 2 precursor. FIGS. 14 and 15 show Co wet-coated Li[Ni 0.9 Co 0.05 Mn 0.05 ] O2 and ordinary Li[Ni 0.9 Co 0.05 Mn 0.05 ] O2 This is a TEM image showing the crystal structure. Figure 16 is a cross-sectional TEM-EDS image of Co wet-coated Li[Ni 0.9 Co 0.05 Mn 0.05 ] O2 cathode material. Fig. 17 shows Co wet-doped Li[Ni 0.9 Co 0.05 Mn 0.05 ] O2 and ordinary Li[Ni 0.9 Co 0.05 Mn 0.05 ] O2 This is an XRD analysis graph showing the crystal structure. Figures 18 and 19 are TEM images showing the crystal structures of Sb dry-doped concentration gradient Li[Ni 0.9 Co 0.05 Mn 0.05] O2 and general concentration gradient Li[Ni 0.9 Co 0.05 Mn 0.05] O2 . Figures 20 and 21 are TEM images showing the crystal structures of Ti wet Mo dry co-doped Li[Ni 0.88 Co 0.06 Mn 0.06 ] O2 and ordinary Li[Ni 0.88 Co 0.06 Mn 0.06 ] O2 . Figure 22 is an XRD analysis graph showing the crystal structures of Ti wet Mo dry co-doped Li[Ni 0.88 Co 0.06 Mn 0.06 ] O2 and ordinary Li[Ni 0.88 Co 0.06 Mn 0.06 ] O2 . FIGS. 23 and 24 are TEM images showing the crystal structures of Ta, Al dry co-doped Li[Ni 0.89 Co 0.1 Al 0.01 ] O2 a