Lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-10840508-B2
Application number	US-201816230697-A
Country	US
Kind code	B2
Filing date	Dec 21, 2018
Priority date	Nov 14, 2014
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

Provided is a secondary battery, specifically, a secondary battery having excellent stability and improved output characteristic and low temperature characteristic by including a cathode active material in which at least one of metals forming the cathode active material has a concentration gradient in an entire region from a central portion up to a surface portion; and a conductive material mixture in which carbon nanotube is mixed with carbon black at an appropriate ratio, the carbon black being a spherical nanoparticle.

First claim

The invention claimed is:

1. A secondary battery comprising:
a conductive material mixture including a linear shape conductive material mixed with a spherical shape conductive material;
wherein the content of the spherical shape conductive material is higher than the content of the linear shape conductive material; and
a cathode active material of the following formula:
Li x M1 a M2 b M3 c O y

wherein M1, M2 and M3 are at least one selected from the group consisting of Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga and B,
wherein x, y, a, b, and c satisfy the relationships
0< x ≤1.1, 2≤ y ≤2.02, 0≤ a≤ 1, 0≤ b≤ 1, 0≤ c≤ 1, 0< a+b+c≤ 1

wherein at least one of the M1, M2, and M3 has a continuous concentration gradient region from a central portion up to a surface portion of a cathode active material particle formed by the cathode active material,
wherein the concentration difference of the M1 between the central portion and a region extended from 5/7 μm radius from the central portion is lower than the concentration difference of the M1 between the surface portion and a region extended from 5/7 μm radius from the surface portion, and
wherein the spherical shape conductive material and the linear shape conductive material are mixed at a mixing ratio of the spherical shape conductive material over the linear shape conductive material of 4:1 to 3:2.

2. The secondary battery of claim 1 , wherein the linear shape conductive material is a carbon nanotube.

3. The secondary battery of claim 1 , wherein the spherical shape conductive material is a carbon black.

4. The secondary battery of claim 1 , wherein at least one of the M1, M2, and M3 has a concentration gradient region in which a concentration is increased from the central portion up to the surface portion, and the remainder has a concentration gradient region in which a concentration is decreased from the central portion up to the surface portion.

5. The secondary battery of claim 1 , wherein any one of the M1, M2, and M3 has a predetermined concentration from the central portion up to the surface portion, and another one has a concentration gradient region in which a concentration is increased from the central portion up to the surface portion, and the other one has a concentration gradient region in which a concentration is decreased from the central portion up to the surface portion.

6. The secondary battery of claim 1 , wherein the M1 is Ni, the M2 is Mn, and the M3 is Co.

7. The secondary battery of claim 1 , wherein the M1 is Ni, and 0.6≤a≤0.95 and 0.05≤b+c≤0.4 are satisfied.

8. The secondary battery of claim 1 , wherein the M1 is Ni, and 0.7≤a≤0.9 and 0.1≤b+c≤0.3 are satisfied.

9. The secondary battery of claim 1 , wherein the conductive material mixture has a content of 2 to 8 wt % relative to 100 wt % of the cathode active material.

10. The secondary battery of claim 1 ,
wherein the central portion has a radius of 0.1 μm to 0.2 μm from the center of the cathode active material particle, and
wherein the surface portion has a radius of 0.1 to 0.2 μm from the outermost of the cathode active material particle.

11. A secondary battery comprising:
a conductive material including a spherical shape conductive material and a linear shape conductive material, wherein the content of the spherical shape conductive material is higher than the content of the linear shape conductive material; and
a cathode active material of the formula
Li x M1 a M2bM3 c O y

wherein M1, M2 and M3 are at least one selected from the group consisting of Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga and B,
wherein x, y, a, b, and c satisfy the relationships 0<x≤1.1, 2≤y≤2.02, 0≤a≤1, 0≤b≤1, 0≤c≤1, 0<a+b+c≤1,
wherein a first one of the M1, M2, and M3 has a constant concentration from a central portion to a surface portion of a cathode active material particle formed by the cathode active material, a second one of the M1, M2, and M3 has an increasing concentration gradient region from the central portion to the surface portion of the cathode active material particle, and a third one of the M1, M2, and M3 has an increasing concentration gradient region form the central portion to the surface portion of the cathode active material particle,
wherein the central portion of the cathode active material particle has a radius of 0.1 to 0.2 μm from the center of the cathode active material particle, and the surface portion of the cathode active material particle has a radius of 0.1 to 0.2 μm from the outermost surface of the cathode active material particle, and
wherein the conductive material includes the spherical shape conductive material and the linear shape conductive material mixed at a mixing ratio of the spherical shape conductive material over the linear shape conductive material of 4:1 to 3:2.

12. The secondary battery of claim 11 , wherein the M1, M2, and M3 are selected form the group consisting of Ni, Co, and Mn.

13. The secondary battery of claim 11 , wherein the M1 is Ni, the M2 is Mn, and the M3 is Co.

14. The secondary battery of claim 11 , wherein the concentration difference of the M1 between the central portion and a region extended 5/7 μm radius from the central portion is lower than the concentration difference of the M1 between the surface portion and a region extended 5/7 μm radius from the surface portion.

Assignees

• Sk Innovation Co Ltd

Inventors

• Lim Jin-Sub
• Han Kook-Hyun
• Hwang Duck-Chul

Classifications

• H01M4/485 Primary

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

• H01M4/525

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

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M4/505

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

• H01M4/625

  Carbon or graphite · CPC title