Positive electrode active material for lithium ion secondary battery, and positive electrode for lithium ion secondary battery and lithium ion secondary battery comprising the same

Patent metadata

Field	Value
Publication number	US-10388944-B2
Application number	US-201514868746-A
Country	US
Kind code	B2
Filing date	Sep 29, 2015
Priority date	Oct 6, 2014
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

A positive electrode active material includes a primary particle represented by Compositional Formula (1):

Li 1+x Ni y Co z M 1−x−y−z O 2   (1),

where x is a number satisfying a relation represented by an expression −0.12≤x≤0.2; y is a number satisfying a relation represented by an expression 0.7≤y≤0.9; z is a number satisfying a relation represented by an expression 0.05≤z≤0.3; and M is at least one element selected from the group consisting of Mg, Al, Ti, Mn, Zr, Mo, and Nb; or a secondary particle into which the primary particle aggregates. The primary particle or the secondary particle includes a free lithium compound in a weight proportion of 0.1% or more and 2.0% or less, and the weight of lithium hydroxide in the free lithium compound is 60% or less of the weight of lithium carbonate in the free lithium compound.

First claim

What is claimed is:

1. A positive electrode active material for a lithium ion secondary battery, comprising:
a secondary particle into which a primary particle aggregates, wherein the primary particle is represented by Compositional Formula (1):
Li 1+x Ni y Co z M 1−x−y−z O 2   (1)

where x is a number satisfying a relation represented by an expression −0.12≤x≤0.2; y is a number satisfying a relation represented by an expression 0.7≤y≤0.9; z is a number satisfying a relation represented by an expression 0.05≤z≤0.3; and M is at least one element selected from the group consisting of Mg, Al, Ti, Mn, Zr, Mo, and Nb;
wherein the primary particle and the secondary particle comprise a free lithium compound in a weight proportion of 0.1% or more and 2.0% or less, and the weight of lithium hydroxide in the free lithium compound is 60% or less of the weight of lithium carbonate in the free lithium compound;
wherein the secondary particle has an open pore, and an open pore volume ratio is 7% or more and 20% or less at a micropore diameter ranging from 0.1 μm or more to 0.5 μm or less, the open pore volume being determined by mercury porosimetry.

2. The positive electrode active material for a lithium ion secondary battery according to claim 1 , wherein the weight proportion of the free lithium compound comprised in the primary particle and the secondary particle is 0.1% or more and 1.0% or less.

3. The positive electrode active material for a lithium ion secondary battery according to claim 1 , wherein a Ni concentration on the surface of the primary particle or the secondary particle is lower than a Ni concentration near the center of the primary particle or the secondary particle.

4. The positive electrode active material for a lithium ion secondary battery according to claim 1 , wherein the average particle diameter of the primary particle is 0.1 μm or more and 2 μm or less.

5. The positive electrode active material for a lithium ion secondary battery according to claim 1 , wherein the weight proportion of the free lithium compound comprised in the primary particle or the secondary particle is 0.1% or more and 1.0% or less, and a Ni concentration on the surface of the primary particle or the secondary particle is lower than a Ni concentration near the center of the primary particle or the secondary particle, and the average particle diameter of the primary particle is 0.1 μm or more and 2 μm or less.

6. The positive electrode active material for a lithium ion secondary battery according to claim 1 , wherein the content of lithium carbonate in the primary particle and the secondary particle is 0.07% by weight or more and 1.50% by weight or less.

7. The positive electrode active material for a lithium ion secondary battery according to claim 1 , wherein a BET specific surface area of the positive electrode active material is 0.2 m 2 /g or more and 1.0 m 2 /g or less.

8. A positive electrode for a lithium ion secondary battery formed from the positive electrode active material according to claim 1 .

9. The positive electrode for a lithium ion secondary battery according to claim 8 , wherein the weight proportion of the free lithium compound comprised in the primary particle and the secondary particle is 0.1% or more and 1.0% or less.

10. The positive electrode for a lithium ion secondary battery according to claim 8 , wherein a Ni concentration on the surface of the primary particle or the secondary particle is lower than a Ni concentration near the center of the primary particle or the secondary particle.

11. The positive electrode for a lithium ion secondary battery according to claim 8 , wherein the average particle diameter of the primary particle is 0.1 μm or more and 2 μm or less.

12. A lithium ion secondary battery, comprising the positive electrode according to claim 8 .

Assignees

• Hitachi Metals Ltd

Inventors

• Toyama Tatsuya
• Takahashi Shin
• Gunji Akira
• Feng Xiaoliang
• Tokoro Hisato
• Nakabayashi Takashi
• Takano Shuichi
• Furutsuki Sho

Classifications

• H01M4/382

  Lithium (H01M4/405 takes precedence) · CPC title

• H01M4/483

  for non-aqueous cells (H01M4/485 takes precedence) · CPC title

• H01M4/485

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title

• H01M4/364

  as mixtures · CPC title

• H01M4/131 Primary

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