Positive electrode for secondary battery, and secondary battery

Patent metadata

Field	Value
Publication number	US-11450852-B2
Application number	US-201916689387-A
Country	US
Kind code	B2
Filing date	Nov 20, 2019
Priority date	May 31, 2017
Publication date	Sep 20, 2022
Grant date	Sep 20, 2022

Abstract

A positive electrode with a positive electrode current collector and a positive electrode mixture layer, and the positive electrode mixture layer has first and second positive electrode mixture layers. The first positive electrode mixture layer comprises a positive electrode active material composed of compound A that contains Ni, Co, Al and Li. The second positive electrode mixture layer is disposed between the first positive electrode mixture layer and the positive electrode current collector, and comprises a positive electrode active material including: said compound A; and a Li-containing compound B which is smaller in specific capacity (mAh/g) and average particle diameter than said compound A. In said compound A, a ratio of Ni to the total number of moles of the metal elements except Li is 82 mol % or more. The average particle diameter of said compound B is 55% or less of the average particle diameter of said compound A.

First claim

The invention claimed is:

1. A positive electrode for a secondary battery, comprising:
a positive electrode current collector; and
positive electrode mixture layers, wherein
the positive electrode mixture layers have a first positive electrode mixture layer including a positive electrode active material composed of a Ni, Co, Al and Li-containing compound A, and a second positive electrode mixture layer disposed between the first positive electrode mixture layer and the positive electrode current collector and including a positive electrode active material including the compound A and a Li-containing compound B having a lower specific capacity (mAh/g) and a smaller average particle size than the compound A,
a Ni content of the compound A is 82 mol % or more based on a total number of moles of metallic elements except for Li, and
an average particle size of the compound B is 55% or less of an average particle size of the compound A,
wherein the compound B includes at least any one of a Ni, Co, Mn and Li-containing compound and a Ni, Co, Al and Li-containing compound having a Ni content of less than 82 mol % based on the total number of moles of metallic elements except for Li.

2. The positive electrode for a secondary battery according to claim 1 , wherein a content of the compound B is in the range of 1 mass % to 50 mass % based on a total amount of the positive electrode mixture layers.

3. The positive electrode for a secondary battery according to claim 1 , wherein the specific capacity of the compound B is in the range of 60% to 98% of a specific capacity of the compound A.

4. The positive electrode for a secondary battery according to claim 1 , wherein the second positive electrode mixture layer includes an insulating inorganic material.

5. The positive electrode for a secondary battery according to claim 1 , wherein a ratio of a thickness of the first positive electrode mixture layer to a total thickness of the positive electrode mixture layers is 40% to 95%, and a ratio of a thickness of the second positive electrode mixture layer to the total thickness of the positive electrode mixture layers is 5% to 60%.

6. A secondary battery comprising:
the positive electrode according to claim 1 ;
a negative electrode; and
an electrolyte.

7. The positive electrode for a secondary battery according to claim 1 ,
wherein the Ni, Co, Al and Li-containing compound A is expressed by the following general formula:
Li x Ni y Co α Al β M γ O 2-z   (1)

wherein, x, y, α, β, γ and z satisfy 0.95<x<1.2, 0.82≤y<1, 0<α≤0.15, 0<β≤0.03, 0≤γ≤0.02, y+α+β+γ=1, and 0≤z<0.05, respectively and M is at least one element except for Li, Ni, Co, Al.

8. The positive electrode for a secondary battery according to claim 7 ,
wherein M is at least one element selected from Fe, Mg, Ti, Cr, Cu, Ze, Sn, Zr, Nb, Mo, Ta, W, Na, K, Ba, Sr, Bi, Be and B.

9. The positive electrode for a secondary battery according to claim 1 ,
wherein the Li-containing compound B is expressed by the following general formula:
Li x Ni y Co α Mn β M γ O 2-z   (2)

wherein, x, y, α, β, γ and z satisfy 0.95<x<1.2, 0.3≤y<0.82, 0<α≤0.4, 0<β≤0.4, 0≤γ≤0.02, y+α+β+γ=1, and 0≤z<0.05, respectively and M is at least one element except for Li, Ni, Co, Mn.

10. The positive electrode for a secondary battery according to claim 9 ,
wherein M is at least one element selected from Fe, Mg, Ti, Cr, Cu, Ze, Sn, Zr, Nb, Mo, Ta, W, Na, K, Ba, Sr, Bi, Be and B.

11. The positive electrode for a secondary battery according to claim 9 ,
wherein the average particle size of the compound B is in a range of ⅕ to ½ of the average particle size of the compound A.

12. The positive electrode for a secondary battery according to claim 1 ,
wherein the positive electrode active material of the second positive electrode mixture layer including the compound A and the Li-containing compound B is configured so that the compound A is a core part and the Li-containing compound B is a shell part disposed on a surface of the core part.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Takezawa Hideharu
• Shiozaki Tomoki

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M4/525 Primary

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title

• H01M4/505

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

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/131

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