Cathode active material for lithium secondary battery and lithium secondary battery including the same

Patent metadata

Field	Value
Publication number	US-12113217-B2
Application number	US-202318501932-A
Country	US
Kind code	B2
Filing date	Nov 3, 2023
Priority date	Nov 8, 2022
Publication date	Oct 8, 2024
Grant date	Oct 8, 2024

Abstract

Cathode active materials for lithium secondary batteries and lithium secondary batteries including the cathode active materials are disclosed. In some implementations, a cathode active material for a lithium secondary battery includes a lithium metal phosphate particle having a crystallite size in a range from 150 nm to 450 nm in a direction of a crystallographic plane (020) as measured by an X-ray diffraction (XRD) analysis. In some implementations, a lithium secondary battery includes a cathode including a cathode active material layer that includes a cathode active material for a lithium secondary battery, and an anode facing the cathode. In some implementations, an electrode crystallite size ratio defined by Equation 4 is in a range from 0.5 to 0.9.

First claim

What is claimed is:

1. A cathode active material for a lithium secondary battery comprising a lithium metal phosphate particle having a crystallite size in a range from 150 nm to 450 nm in a direction of a crystallographic plane (020) as measured by an X-ray diffraction (XRD) analysis,
wherein a particle crystallite size ratio determined by Equation 2 based on a measurement by the XRD analysis is greater than 0 and less than 1:
particle crystallite size ratio= Lp (020)/ Lp (200)  [Equation 2]

wherein, in Equation 2, Lp(020) is a value in nm corresponding to the crystallite size in the direction of the crystallographic plane (020) of the lithium metal phosphate particle, and Lp(200) is a value in nm corresponding to a crystallite size in a direction of a crystallographic plane (020) of the lithium metal phosphate particle.

2. The cathode active material according to claim 1 , wherein the crystallite size of the lithium metal phosphate particle in the direction of the crystallographic plane (020) is in a range from 250 nm to 400 nm.

3. The cathode active material according to claim 1 , wherein the crystallite size of the lithium metal phosphate particle in the direction of the crystallographic plane (020) is measured using Equation 1:

Lp
⁡
(
020
)

=

0
.
9

⁢
λ

β
⁢
cos
⁢
θ

[

Equation
⁢

1

]

wherein, in Equation 1, Lp(020) is a value in nm corresponding to the crystallite size of the lithium metal phosphate particle in the direction of the crystallographic plane (020), λ is a value in nm corresponding to an X-ray wavelength used in the XRD analysis, β is a value in rad indicating a full width at half maximum of a peak corresponding to the crystallographic plane (020), and θ is a diffraction angle in rad.

4. The cathode active material according to claim 1 , wherein Lp(200) of Equation 2 is measured using Equation 3:

Lp
⁡
(
200
)

=

0
.
9

⁢
λ

β
⁢
cos
⁢
θ

[

Equation
⁢

3

]

wherein, in Equation 3, Lp(200) is the value in nm corresponding to the crystallite size of the lithium metal phosphate particle in the direction of the crystallographic plane (020), λ is a value in nm corresponding to an X-ray wavelength used in the XRD analysis, β is a value in rad indicating a full width at half maximum of a peak corresponding to the crystallographic plane (020), and θ is a diffraction angle in rad.

5. The cathode active material according to claim 1 , wherein the particle crystallite size ratio is in a range from 0.80 to 0.99.

6. The cathode active material according to claim 1 , wherein the lithium metal phosphate particle includes an olivine crystal structure represented by Chemical Formula 1:
Li a M x P y O 4+z   [Chemical Formula 1]

wherein, in Chemical Formula 1, 0.9≤a≤1.2, 0.99≤x≤1.01, 0.9≤y≤1.2,−0.1≤z≤0.1, and M includes at least one of Fe, Co, Ni, or Mn.

7. The cathode active material according to claim 1 , wherein the lithium metal phosphate particle further includes a doping element or a coating element, and
the doping element or the coating element includes at least one of Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Al, Ga, C, Si, Sn, Sr, Ba, Ra, P, or Zr.

8. The cathode active material according to claim 1 , wherein the lithium metal phosphate particle further includes a carbon coating formed on a surface of the lithium metal phosphate particle.

9. The cathode active material according to claim 1 , wherein the direction of the crystallographic plane (020) of the lithium metal phosphate particle is a direction in which lithium ions are diffused or transferred.

10. A lithium secondary battery, comprising:
a cathode comprising a cathode active material layer that includes a cathode active material for a lithium secondary battery; and
an anode facing the cathode,
wherein an electrode crystallite size ratio determined by Equation 4 is in a range from 0.5 to 0.9:
electrode crystallite size ratio= Le (020)/ Le (200)  [Equation 4]

wherein, in Equation 4, Le(020) is a value in nm corresponding to a crystallite size in a direction of a crystallographic plane (020) measured by an XRD analysis on the cathode active material layer, and Le(200) is a value in nm corresponding to a crystallite size in a direction of a direction of a crystallographic plane (020) measured by the XRD analysis on the cathode active material layer.

11. The lithium secondary battery according to claim 10 , wherein Le(020) in Equation 4 is measured using Equation 5, and Le(200) in Equation 4 is measured using Equation 6:

Le
⁡
(
020
)

=

0
.
9

⁢
λ

β
⁢
cos
⁢
θ

[

Equation
⁢

5

Assignees

• Sk Innovation Co Ltd
• Sk On Co Ltd

Inventors

• Do Ji Yae
• Kang Min Suk
• Beak Min Cheol
• Lee Kwang Ho
• Choi Wan Uk

Classifications

• H01M2004/028

  Positive electrodes · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/131

  Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title

• C01P2006/40

  Electric properties · CPC title