Lithium composite metal oxide, positive electrode active material for lithium secondary battery, positive electrode for lithium secondary battery, and lithium secondary battery

Patent metadata

Field	Value
Publication number	US-2021017039-A1
Application number	US-201916982001-A
Country	US
Kind code	A1
Filing date	Mar 22, 2019
Priority date	Mar 23, 2018
Publication date	Jan 21, 2021
Grant date	—

Abstract

A lithium composite metal oxide containing a secondary particle that is an aggregate of primary particles, in which, when a cross-sectional image of the secondary particle is acquired, and the cross-sectional image is observed, a content proportion of reference primary particles present in a central part of the secondary particle is 20% or more and 50% or less, and a content proportion of reference primary particles present in a surface part of the secondary particle is 30% or more and 100% or less.

First claim

1 . A lithium composite metal oxide comprising:
a secondary particle that is an aggregate of primary particles, wherein, when a cross-sectional image of the secondary particle is acquired, and the cross-sectional image is observed, a content proportion of reference primary particles present in a central part of the secondary particle is 20% or more and 50% or less, and a content proportion of reference primary particles present in a surface part of the secondary particle is 30% or more and 100% or less, (here, the reference primary particles refer to primary particles that are observed in the cross-sectional image of the secondary particle and have an aspect ratio of 2.0 or more, the central part refers to a part surrounded by an imaginary circle, which has a center at a centroid position of a figure surrounded by an outer edge of the cross-sectional image of the secondary particle and has a radius of r calculated from the following expression in which an area of the figure is denoted by S,
r= ( S/π ) 0.5 /2
the surface part refers to a part obtained by removing the imaginary circle from the figure).

2 . A lithium composite metal oxide comprising:
a secondary particle that is an aggregate of primary particles, wherein, in a surface part of the secondary particle, the primary particles that have an elongated shape are radially arranged and aggregated outward from a center of the secondary particle, a content proportion of reference primary particles present in a central part of the secondary particle is lower than a proportion of the reference primary particles present in the surface part, when a cross-sectional image of the secondary particle is acquired, and the cross-sectional image is observed, the content proportion of the reference primary particles present in the central part of the secondary particle is 20% or more and 50% or less, and the content proportion of the reference primary particles present in the surface part of the secondary particle is 30% or more and 100% or less, (here, the reference primary particles refer to primary particles that are observed in the cross-sectional image of the secondary particle and have an aspect ratio of 2.0 or more, the central part refers to a part surrounded by an imaginary circle, which has a center at a centroid position of a figure surrounded by an outer edge of the cross-sectional image of the secondary particle and has a radius of r calculated from the following expression in which an area of the figure is denoted by S,
r= ( S/π ) 0.5 /2
the surface part refers to a part obtained by removing the imaginary circle from the figure).

3 . The lithium composite metal oxide according to claim 2 ,
wherein the content proportion of the reference primary particles present in the central part of the secondary particles is 20% or more and less than 40%, and the content proportion of the reference primary particles present in the surface part of the secondary particles is 40% or more and 100% or less.

4 . The lithium composite metal oxide according to claim 1 ,
wherein, in the cross-sectional image, a difference between an average value of aspect ratios of the primary particles present in the central part of the secondary particle and an average value of aspect ratios of the primary particles present in the surface part of the secondary particles is 0.30 or more and 1.0 or less.

5 . The lithium composite metal oxide according to claim 1 ,
wherein, in the cross-sectional image, an average value of the aspect ratios of the primary particles present in the surface part of the secondary particle is 1.85 or more and 3.00 or less.

6 . The lithium composite metal oxide according to claim 1 ,
wherein, in the cross-sectional image, an average value of the aspect ratios of the primary particles present in the central part of the secondary particle is 1.66 or more and 2.00 or less.

7 . The lithium composite metal oxide according to claim 1 ,
wherein the lithium composite metal oxide is represented by Formula (I),
Li[Li x (Ni (1−y−z−w) Co y Mn z M w ) 1−x ]O 2   (I)

(in Formula (I), −0.1≤x≤0.2, 0≤y≤0.5, 0≤z≤0.5, 0≤w≤0.1, and y+z+w<1 are satisfied, and M represents one or more elements selected from the group consisting of Mg, Ca, Sr, Ba, Zn, B, Al, Ga, Ti, Zr, Ge, Fe, Cu, Cr, V, W, Mo, Sc, Y, Nb, La, Ta, Tc, Ru, Rh, Pd, Ag, Cd, In, and Sn).

8 . The lithium composite metal oxide according to claim 7 ,
wherein a range of x in Formula (I) satisfies 0<x≤0.2.

9 . A positive electrode active material for a lithium secondary battery, comprising:
the lithium composite metal oxide according to claim 1 .

10 . A positive electrode for a lithium secondary battery, comprising:
the positive electrode active material for a lithium secondary battery according to claim 9 .

11 . A lithium secondary battery comprising:
the positive electrode for a lithium secondary battery according to claim 10 .

Assignees

• Sumitomo Chemical Co
• Tanaka Chemical Corp

Inventors

• Nagao Daisuke
• Kageura Jun-Ichi
• Maeda Yusuke

Classifications

• C01P2004/54

  Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension · CPC title

• C01G53/82 Primary

  Compounds containing nickel, with or without oxygen or hydrogen, and containing two or more other elements · CPC title

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M4/131

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

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title